Network initiated release assistance indication

ABSTRACT

A session management function (SMF) receives a message from a network exposure function (NEF). The message comprises downlink data and a release assistance indicator (RAI). The RAI indicates that transmission of uplink data by a wireless device is expected subsequent to transmission of the downlink data. The RAI indicates a release of a connection associated with the wireless device after the transmission of uplink data. The SMF receives an indication that the uplink data is transmitted. The SMF upon receiving the indication, sends a release message to an access and mobility management function (AMF). The release message indicates release of a non-access stratum message associated with the wireless device. The release message comprises the release assistance indicator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 62/736,238, filed Sep. 25, 2018, which is hereby incorporated by reference in its entirety.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Examples of several of the various embodiments of the present invention are described herein with reference to the drawings.

FIG. 1 is a diagram of an example 5G system architecture as per an aspect of an embodiment of the present disclosure.

FIG. 2 is a diagram of an example 5G System architecture as per an aspect of an embodiment of the present disclosure.

FIG. 3 is a system diagram of an example wireless device and a network node in a 5G system as per an aspect of an embodiment of the present disclosure.

FIG. 4 is a system diagram of an example wireless device as per an aspect of an embodiment of the present disclosure.

FIG. 5A and FIG. 5B depict two registration management state models in UE 100 and AMF 155 as per an aspect of embodiments of the present disclosure.

FIG. 6A and FIG. 6B depict two connection management state models in UE 100 and AMF 155 as per an aspect of embodiments of the present disclosure.

FIG. 7 is diagram for classification and marking traffic as per an aspect of an embodiment of the present disclosure.

FIG. 8 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 9 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 10 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 11 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 12 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 13 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 14 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 15 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 16 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 17 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 18 is an example description as per an aspect of an embodiment of the present disclosure.

FIG. 19 is an example description as per an aspect of an embodiment of the present disclosure.

FIG. 20 is an example description as per an aspect of an embodiment of the present disclosure.

FIG. 21 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 22 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 23 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 24 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 25 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 26 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 27 is an example call flow as per an aspect of an embodiment of the present disclosure.

FIG. 28 is an example description as per an aspect of an embodiment of the present disclosure.

FIG. 29 is an example description as per an aspect of an embodiment of the present disclosure.

FIG. 30 is an example depicting an information element as per an aspect of an embodiment of the present disclosure.

FIG. 31 is an example depicting an information element as per an aspect of an embodiment of the present disclosure.

FIG. 32 is an example depicting an information element as per an aspect of an embodiment of the present disclosure.

FIG. 33 is an example flowchart as per an aspect of an embodiment of the present disclosure.

FIG. 34 is an example flowchart as per an aspect of an embodiment of the present disclosure.

FIG. 35 is an example flowchart as per an aspect of an embodiment of the present disclosure.

FIG. 36 is an example flowchart as per an aspect of an embodiment of the present disclosure.

FIG. 37 is a flow diagram as per an aspect of an example embodiment of the present disclosure.

DETAILED DESCRIPTION OF EXAMPLES

Example embodiments of the present invention enable implementation of enhanced features and functionalities in 5G systems. Embodiments of the technology disclosed herein may be employed in the technical field of 5G systems, 5G Cellular Internet of Things (IoT), Machine Type Communication (MTC), and network slicing for communication systems. More particularly, the embodiments of the technology disclosed herein may relate to 5G core network and 5G systems for 5G Cellular Internet of Things (IoT), Machine Type Communication (MTC), and network slicing in communication systems. Throughout the present disclosure, UE, wireless device, and mobile device are used interchangeably. Throughout the present disclosure, CIoT, and MTC are used interchangeably.

The following acronyms are used throughout the present disclosure:

5G 5th generation mobile networks

5GC 5G Core Network

5GS 5G System

5G-AN 5G Access Network

5QI 5G QoS Indicator

AF Application Function

AMF Access and Mobility Management Function

AN Access Network

AS Application Server

CDR Charging Data Record

CCNF Common Control Network Functions

CIoT Cellular IoT

CN Core Network

CP Control Plane

DDN Downlink Data Notification

DL Downlink

DN Data Network

DNN Data Network Name

F-TEID Fully Qualified TEID

FQDN Fully Qualified Domain Name

GPSI Generic Public Subscription Identifier

GTP GPRS Tunneling Protocol

GUTI Globally Unique Temporary Identifier

IMSI International Mobile Subscriber Identity

IoT Internet of Things

LADN Local Area Data Network

LI Lawful Intercept

MEI Mobile Equipment Identifier

MICO Mobile Initiated Connection Only

MME Mobility Management Entity

MO Mobile Originated

MSISDN Mobile Subscriber ISDN

MT Mobile Terminating

MTC Machine Type Communication

N3IWF Non-3GPP InterWorking Function

NAI Network Access Identifier

NAS Non-Access Stratum

NB-IoT Narrow Band IoT

NEF Network Exposure Function

NF Network Function

NGAP Next Generation Application Protocol

NIMF Network IoT Messaging Function

NR New Radio

NRF Network Repository Function

NSI Network Slice Instance

NSSAI Network Slice Selection Assistance Information

NSSF Network Slice Selection Function

OCS Online Charging System

OFCS Offline Charging System

PCF Policy Control Function

PDU Packet/Protocol Data Unit

PEI Permanent Equipment Identifier

PLMN Public Land Mobile Network

RAN Radio Access Network

QFI QoS Flow Identity

RM Registration Management

S1-AP S1 Application Protocol

SBA Service Based Architecture

SEA Security Anchor Function

SCM Security Context Management

SCS Service Capability Server

SMF Session Management Function

SMSF SMS Function

S-NSSAI Single Network Slice Selection Assistance information

SUCI Served User Correlation ID

SUPI Subscriber Permanent Identifier

TEID Tunnel Endpoint Identifier

UE User Equipment

UL Uplink

UL CL Uplink Classifier

UPF User Plane Function

URRP UE Reachability Request Parameter

Example FIG. 1 and FIG. 2 depict a 5G system comprising of access networks and 5G core network. An example 5G access network may comprise an access network connecting to a 5G core network. An access network may comprise an NG-RAN 105 and/or non-3GPP AN 165. An example 5G core network may connect to one or more 5G access networks 5G-AN and/or NG-RANs. 5G core network may comprise functional elements or network functions as in example FIG. 1 and example FIG. 2 where interfaces may be employed for communication among the functional elements and/or network elements.

In an example, a network function may be a processing function in a network, which may have a functional behavior and/or interfaces. A network function may be implemented either as a network element on a dedicated hardware, and/or a network node as depicted in FIG. 3 and FIG. 4, or as a software instance running on a dedicated hardware and/or shared hardware, or as a virtualized function instantiated on an appropriate platform.

In an example, access and mobility management function, AMF 155, may include the following functionalities (some of the AMF 155 functionalities may be supported in a single instance of an AMF 155): termination of RAN 105 CP interface (N2), termination of NAS (N1), NAS ciphering and integrity protection, registration management, connection management, reachability management, mobility management, lawful intercept (for AMF 155 events and interface to LI system), provide transport for session management, SM messages between UE 100 and SMF 160, transparent proxy for routing SM messages, access authentication, access authorization, provide transport for SMS messages between UE 100 and SMSF, security anchor function, SEA, interaction with the AUSF 150 and the UE 100, receiving the intermediate key established as a result of the UE 100 authentication process, security context management, SCM, that receives a key from the SEA that it uses to derive access network specific keys, and/or the like.

In an example, the AMF 155 may support non-3GPP access networks through N2 interface with N3IWF 170, NAS signaling with a UE 100 over N3IWF 170, authentication of UEs connected over N3IWF 170, management of mobility, authentication, and separate security context state(s) of a UE 100 connected via non-3GPP access 165 or connected via 3GPP access 105 and non-3GPP access 165 simultaneously, support of a coordinated RM context valid over 3GPP access 105 and non 3GPP access 165, support of CM management contexts for the UE 100 for connectivity over non-3GPP access, and/or the like.

In an example, an AMF 155 region may comprise one or multiple AMF 155 sets. The AMF 155 set may comprise some AMF 155 that serve a given area and/or network slice(s). In an example, multiple AMF 155 sets may be per AMF 155 region and/or network slice(s). Application identifier may be an identifier that may be mapped to a specific application traffic detection rule. Configured NSSAI may be an NSSAI that may be provisioned in a UE 100. DN 115 access identifier (DNAI), for a DNN, may be an identifier of a user plane access to a DN 115. Initial registration may be related to a UE 100 registration in RM-DEREGISTERED 500, 520 states. N2AP UE 100 association may be a logical per UE 100 association between a 5G AN node and an AMF 155. N2AP UE-TNLA-binding may be a binding between a N2AP UE 100 association and a specific transport network layer, TNL association for a given UE 100.

In an example, session management function, SMF 160, may include one or more of the following functionalities (one or more of the SMF 160 functionalities may be supported in a single instance of a SMF 160): session management (e.g. session establishment, modify and release, including tunnel maintain between UPF 110 and AN 105 node), UE 100 IP address allocation & management (including optional authorization), selection and control of UP function(s), configuration of traffic steering at UPF 110 to route traffic to proper destination, termination of interfaces towards policy control functions, control part of policy enforcement and QoS, lawful intercept (for SM events and interface to LI System), termination of SM parts of NAS messages, downlink data notification, initiation of AN specific SM information, sent via AMF 155 over N2 to (R)AN 105, determination of SSC mode of a session, roaming functionality, handling local enforcement to apply QoS SLAs (VPLMN), charging data collection and charging interface (VPLMN), lawful intercept (in VPLMN for SM events and interface to LI System), support for interaction with external DN 115 for transport of signaling for PDU session authorization/authentication by external DN 115, and/or the like.

In an example, a user plane function, UPF 110, may include one or more of the following functionalities (some of the UPF 110 functionalities may be supported in a single instance of a UPF 110): anchor point for Intra-/Inter-RAT mobility (when applicable), external PDU session point of interconnect to DN 115, packet routing & forwarding, packet inspection and user plane part of policy rule enforcement, lawful intercept (UP collection), traffic usage reporting, uplink classifier to support routing traffic flows to a data network, branching point to support multi-homed PDU session(s), QoS handling for user plane, uplink traffic verification (SDF to QoS flow mapping), transport level packet marking in the uplink and downlink, downlink packet buffering, downlink data notification triggering, and/or the like.

In an example, the UE 100 IP address management may include allocation and release of the UE 100 IP address and/or renewal of the allocated IP address. The UE 100 may set a requested PDU type during a PDU session establishment procedure based on its IP stack capabilities and/or configuration. In an example, the SMF 160 may select PDU type of a PDU session. In an example, if the SMF 160 receives a request with PDU type set to IP, the SMF 160 may select PDU type IPv4 or IPv6 based on DNN configuration and/or operator policies. In an example, the SMF 160 may provide a cause value to the UE 100 to indicate whether the other IP version is supported on the DNN. In an example, if the SMF 160 receives a request for PDU type IPv4 or IPv6 and the requested IP version is supported by the DNN the SMF 160 may select the requested PDU type.

In an example embodiment, the 5GC elements and UE 100 may support the following mechanisms: during a PDU session establishment procedure, the SMF 160 may send the IP address to the UE 100 via SM NAS signaling. The IPv4 address allocation and/or IPv4 parameter configuration via DHCPv4 may be employed once PDU session may be established. IPv6 prefix allocation may be supported via IPv6 stateless autoconfiguration, if IPv6 is supported. In an example, 5GC network elements may support IPv6 parameter configuration via stateless DHCPv6.

The 5GC may support the allocation of a static IPv4 address and/or a static IPv6 prefix based on subscription information in a UDM 140 and/or based on the configuration on a per-subscriber, per-DNN basis.

User plane function(s) (UPF 110) may handle the user plane path of PDU sessions. A UPF 110 that provides the interface to a data network may support functionality of a PDU session anchor.

In an example, a policy control function, PCF 135, may support unified policy framework to govern network behavior, provide policy rules to control plane function(s) to enforce policy rules, implement a front end to access subscription information relevant for policy decisions in a user data repository (UDR), and/or the like.

A network exposure function, NEF 125, may provide means to securely expose the services and capabilities provided by the 3GPP network functions, translate between information exchanged with the AF 145 and information exchanged with the internal network functions, receive information from other network functions, and/or the like.

In an example, an network repository function, NRF 130 may support service discovery function that may receive NF discovery request from NF instance, provide information about the discovered NF instances (be discovered) to the NF instance, and maintain information about available NF instances and their supported services, and/or the like.

In an example, an NSSF 120 may select a set of network slice instances serving the UE 100, may determine allowed NSSAI. In an example, the NSSF 120 may determine the AMF 155 set to be employed to serve the UE 100, and/or, based on configuration, determine a list of candidate AMF 155(s) 155 by querying the NRF 130.

In an example, stored data in a UDR may include at least user subscription data, including at least subscription identifiers, security credentials, access and mobility related subscription data, session related subscription data, policy data, and/or the like.

In an example, an AUSF 150 may support authentication server function (AUSF 150).

In an example, an application function, AF 145, may interact with the 3GPP core network to provide services. In an example, based on operator deployment, application functions may be trusted by the operator to interact directly with relevant network functions. Application functions not allowed by the operator to access directly the network functions may use an external exposure framework (e.g., via the NEF 125) to interact with relevant network functions.

In an example, control plane interface between the (R)AN 105 and the 5G core may support connection of multiple different kinds of AN(s) (e.g. 3GPP RAN 105, N3IWF 170 for Un-trusted access 165) to the 5GC via a control plane protocol. In an example, an N2 AP protocol may be employed for both the 3GPP access 105 and non-3GPP access 165. In an example, control plane interface between the (R)AN 105 and the 5G core may support decoupling between AMF 155 and other functions such as SMF 160 that may need to control the services supported by AN(s) (e.g. control of the UP resources in the AN 105 for a PDU session).

In an example, the 5GC may provide policy information from the PCF 135 to the UE 100. In an example, the policy information may comprise: access network discovery and selection policy, UE 100 route selection policy (URSP), SSC mode selection policy (SSCMSP), network slice selection policy (NSSP), DNN selection policy, non-seamless offload policy, and/or the like.

In an example, as depicted in example FIG. 5A and FIG. 5B, the registration management, RM may be employed to register or de-register a UE/user 100 with the network, and establish the user context in the network. Connection management may be employed to establish and release the signaling connection between the UE 100 and the AMF 155.

In an example, a UE 100 may register with the network to receive services that require registration. In an example, the UE 100 may update its registration with the network periodically in order to remain reachable (periodic registration update), or upon mobility (e.g., mobility registration update), or to update its capabilities or to re-negotiate protocol parameters.

In an example, an initial registration procedure as depicted in example FIG. 8 and FIG. 9 may involve execution of network access control functions (e.g. user authentication and access authorization based on subscription profiles in UDM 140). Example FIG. 9 is a continuation of the initial registration procedure depicted in FIG. 8. As a result of the initial registration procedure, the identity of the serving AMF 155 may be registered in a UDM 140.

In an example, the registration management, RM procedures may be applicable over both 3GPP access 105 and non 3GPP access 165.

An example FIG. 5A may depict the RM states of a UE 100 as observed by the UE 100 and AMF 155. In an example embodiment, two RM states may be employed in the UE 100 and the AMF 155 that may reflect the registration status of the UE 100 in the selected PLMN: RM-DEREGISTERED 500, and RM-REGISTERED 510. In an example, in the RM DEREGISTERED state 500, the UE 100 may not be registered with the network. The UE 100 context in the AMF 155 may not hold valid location or routing information for the UE 100 so the UE 100 may not be reachable by the AMF 155. In an example, the UE 100 context may be stored in the UE 100 and the AMF 155. In an example, in the RM REGISTERED state 510, the UE 100 may be registered with the network. In the RM-REGISTERED 510 state, the UE 100 may receive services that may require registration with the network.

In an example embodiment, two RM states may be employed in AMF 155 for the UE 100 that may reflect the registration status of the UE 100 in the selected PLMN: RM-DEREGISTERED 520, and RM-REGISTERED 530.

As depicted in example FIG. 6A and FIG. 6B, connection management, CM, may comprise establishing and releasing a signaling connection between a UE 100 and an AMF 155 over N1 interface. The signaling connection may be employed to enable NAS signaling exchange between the UE 100 and the core network. The signaling connection between the UE 100 and the AMF 155 may comprise both the AN signaling connection between the UE 100 and the (R)AN 105 (e.g. RRC connection over 3GPP access) and the N2 connection for the UE 100 between the AN and the AMF 155.

As depicted in example FIG. 6A and FIG. 6B, two CM states may be employed for the NAS signaling connectivity of the UE 100 with the AMF 155, CM-IDLE 600, 620 and CM-CONNECTED 610, 630. A UE 100 in CM-IDLE 600 state may be in RM-REGISTERED 510 state and may have no NAS signaling connection established with the AMF 155 over N1. The UE 100 may perform cell selection, cell reselection, PLMN selection, and/or the like. A UE 100 in CM-CONNECTED 610 state may have a NAS signaling connection with the AMF 155 over N1.

In an example embodiment two CM states may be employed for the UE 100 at the AMF 155, CM-IDLE 620 and CM-CONNECTED 630.

In an example, an RRC inactive state may apply to NG-RAN (e.g. it may apply to NR and E-UTRA connected to 5G CN). The AMF 155, based on network configuration, may provide assistance information to the NG RAN 105, to assist the NG RAN's 105 decision whether the UE 100 may be sent to RRC inactive state. When a UE 100 is CM-CONNECTED 610 with RRC inactive state, the UE 100 may resume the RRC connection due to uplink data pending, mobile initiated signaling procedure, as a response to RAN 105 paging, to notify the network that it has left the RAN 105 notification area, and/or the like.

In an example, a NAS signaling connection management may include establishing and releasing a NAS signaling connection. A NAS signaling connection establishment function may be provided by the UE 100 and the AMF 155 to establish the NAS signaling connection for the UE 100 in CM-IDLE 600 state. The procedure of releasing the NAS signaling connection may be initiated by the 5G (R)AN 105 node or the AMF 155.

In an example, reachability management of a UE 100 may detect whether the UE 100 is reachable and may provide the UE 100 location (e.g. access node) to the network to reach the UE 100. Reachability management may be done by paging the UE 100 and the UE 100 location tracking. The UE 100 location tracking may include both UE 100 registration area tracking and UE 100 reachability tracking. The UE 100 and the AMF 155 may negotiate UE 100 reachability characteristics in CM-IDLE 600, 620 state during registration and registration update procedures.

In an example, two UE 100 reachability categories may be negotiated between a UE 100 and an AMF 155 for CM-IDLE 600, 620 state. 1) UE 100 reachability allowing mobile device terminated data while the UE 100 is CM-IDLE 600 mode. 2) Mobile initiated connection only (MICO) mode. The 5GC may support a PDU connectivity service that provides exchange of PDUs between the UE 100 and a data network identified by a DNN. The PDU connectivity service may be supported via PDU sessions that are established upon request from the UE 100.

In an example, a PDU session may support one or more PDU session types. PDU sessions may be established (e.g. upon UE 100 request), modified (e.g. upon UE 100 and 5GC request) and/or released (e.g. upon UE 100 and 5GC request) using NAS SM signaling exchanged over N1 between the UE 100 and the SMF 160. Upon request from an application server, the 5GC may be able to trigger a specific application in the UE 100. When receiving the trigger, the UE 100 may send it to the identified application in the UE 100. The identified application in the UE 100 may establish a PDU session to a specific DNN.

In an example, the 5G QoS model may support a QoS flow based framework as depicted in example FIG. 7. The 5G QoS model may support both QoS flows that require a guaranteed flow bit rate and QoS flows that may not require a guaranteed flow bit rate. In an example, the 5G QoS model may support reflective QoS. The QoS model may comprise flow mapping or packet marking at the UPF 110 (CN_UP) 110, AN 105 and/or the UE 100. In an example, packets may arrive from and/or destined to the application/service layer 730 of UE 100, UPF 110 (CN_UP) 110, and/or the AF 145.

In an example, the QoS flow may be a granularity of QoS differentiation in a PDU session. A QoS flow ID, QFI, may be employed to identify the QoS flow in the 5G system. In an example, user plane traffic with the same QFI within a PDU session may receive the same traffic forwarding treatment. The QFI may be carried in an encapsulation header on N3 and/or N9 (e.g. without any changes to the end-to-end packet header). In an example, the QFI may be applied to PDUs with different types of payload. The QFI may be unique within a PDU session.

In an example, the QoS parameters of a QoS flow may be provided to the (R)AN 105 as a QoS profile over N2 at PDU session establishment, QoS flow establishment, or when NG-RAN is used at every time the user plane is activated. In an example, a default QoS rule may be required for every PDU session. The SMF 160 may allocate the QFI for a QoS flow and may derive QoS parameters from the information provided by the PCF 135. In an example, the SMF 160 may provide the QFI together with the QoS profile containing the QoS parameters of a QoS flow to the (R)AN 105.

In an example, 5G QoS flow may be a granularity for QoS forwarding treatment in the 5G system. Traffic mapped to the same 5G QoS flow may receive the same forwarding treatment (e.g. scheduling policy, queue management policy, rate shaping policy, RLC configuration, and/or the like). In an example, providing different QoS forwarding treatment may require separate 5G QoS flows.

In an example, a 5G QoS indicator may be a scalar that may be employed as a reference to a specific QoS forwarding behavior (e.g. packet loss rate, packet delay budget) to be provided to a 5G QoS flow. In an example, the 5G QoS indicator may be implemented in the access network by the 5QI referencing node specific parameters that may control the QoS forwarding treatment (e.g. scheduling weights, admission thresholds, queue management thresholds, link layer protocol configuration, and/or the like.).

In an example, 5GC may support edge computing and may enable operator(s) and 3rd party services to be hosted close to the UE's access point of attachment. The 5G core network may select a UPF 110 close to the UE 100 and may execute the traffic steering from the UPF 110 to the local data network via a N6 interface. In an example, the selection and traffic steering may be based on the UE's 100 subscription data, UE 100 location, the information from application function AF 145, policy, other related traffic rules, and/or the like. In an example, the 5G core network may expose network information and capabilities to an edge computing application function. The functionality support for edge computing may include local routing where the 5G core network may select a UPF 110 to route the user traffic to the local data network, traffic steering where the 5G core network may select the traffic to be routed to the applications in the local data network, session and service continuity to enable UE 100 and application mobility, user plane selection and reselection, e.g. based on input from application function, network capability exposure where 5G core network and application function may provide information to each other via NEF 125, QoS and charging where PCF 135 may provide rules for QoS control and charging for the traffic routed to the local data network, support of local area data network where 5G core network may provide support to connect to the LADN in a certain area where the applications are deployed, and/or the like.

An example 5G system may be a 3GPP system comprising of 5G access network 105, 5G core network and a UE 100, and/or the like. Allowed NSSAI may be an NSSAI provided by a serving PLMN during e.g. a registration procedure, indicating the NSSAI allowed by the network for the UE 100 in the serving PLMN for the current registration area.

In an example, a PDU connectivity service may provide exchange of PDUs between a UE 100 and a data network. A PDU session may be an association between the UE 100 and the data network, DN 115, that may provide the PDU connectivity service. The type of association may be IP, Ethernet and/or unstructured.

Establishment of user plane connectivity to a data network via network slice instance(s) may comprise the following: performing a RM procedure to select an AMF 155 that supports the required network slices, and establishing one or more PDU session(s) to the required data network via the network slice instance(s).

In an example, the set of network slices for a UE 100 may be changed at any time while the UE 100 may be registered with the network, and may be initiated by the network, or the UE 100.

In an example, a periodic registration update may be UE 100 re-registration at expiry of a periodic registration timer. A requested NSSAI may be a NSSAI that the UE 100 may provide to the network.

In an example, a service based interface may represent how a set of services may be provided/exposed by a given NF.

In an example, a service continuity may be an uninterrupted user experience of a service, including the cases where the IP address and/or anchoring point may change. In an example, a session continuity may refer to continuity of a PDU session. For PDU session of IP type session continuity may imply that the IP address is preserved for the lifetime of the PDU session. An uplink classifier may be a UPF 110 functionality that aims at diverting uplink traffic, based on filter rules provided by the SMF 160, towards data network, DN 115.

In an example, the 5G system architecture may support data connectivity and services enabling deployments to use techniques such as e.g. network function virtualization and/or software defined networking. The 5G system architecture may leverage service-based interactions between control plane (CP) network functions where identified. In 5G system architecture, separation of the user plane (UP) functions from the control plane functions may be considered. A 5G system may enable a network function to interact with other NF(s) directly if required.

In an example, the 5G system may reduce dependencies between the access network (AN) and the core network (CN). The architecture may comprise a converged access-agnostic core network with a common AN-CN interface which may integrate different 3GPP and non-3GPP access types.

In an example, the 5G system may support a unified authentication framework, stateless NFs, where the compute resource is decoupled from the storage resource, capability exposure, and concurrent access to local and centralized services. To support low latency services and access to local data networks, UP functions may be deployed close to the access network.

In an example, the 5G system may support roaming with home routed traffic and/or local breakout traffic in the visited PLMN. An example 5G architecture may be service-based and the interaction between network functions may be represented in two ways. (1) As service-based representation (depicted in example FIG. 1), where network functions within the control plane, may enable other authorized network functions to access their services. This representation may also include point-to-point reference points where necessary. (2) Reference point representation, showing the interaction between the NF services in the network functions described by point-to-point reference point (e.g. N11) between any two network functions.

In an example, a network slice may comprise the core network control plane and user plane network functions, the 5G Radio Access Network; the N3IWF functions to the non-3GPP Access Network, and/or the like. Network slices may differ for supported features and network function implementation. The operator may deploy multiple network slice instances delivering the same features but for different groups of UEs, e.g. as they deliver a different committed service and/or because they may be dedicated to a customer. The NSSF 120 may store the mapping information between slice instance ID and NF ID (or NF address).

In an example, a UE 100 may simultaneously be served by one or more network slice instances via a 5G-AN. In an example, the UE 100 may be served by k network slices (e.g. k=8, 16, etc.) at a time. An AMF 155 instance serving the UE 100 logically may belong to a network slice instance serving the UE 100.

In an example, a PDU session may belong to one specific network slice instance per PLMN. In an example, different network slice instances may not share a PDU session. Different slices may have slice-specific PDU sessions using the same DNN.

An S-NSSAI (Single Network Slice Selection Assistance information) may identify a network slice. An S-NSSAI may comprise a slice/service type (SST), which may refer to the expected network slice behavior in terms of features and services; and/or a slice differentiator (SD). A slice differentiator may be optional information that may complement the slice/service type(s) to allow further differentiation for selecting a network slice instance from potentially multiple network slice instances that comply with the indicated slice/service type. In an example, the same network slice instance may be selected employing different S-NSSAIs. The CN part of a network slice instance(s) serving a UE 100 may be selected by CN.

In an example, subscription data may include the S-NSSAI(s) of the network slices that the UE 100 subscribes to. One or more S-NSSAIs may be marked as default S-NSSAI. In an example, k S-NSSAI may be marked default S-NSSAI (e.g. k=8, 16, etc.). In an example, the UE 100 may subscribe to more than 8 S-NSSAIs.

In an example, a UE 100 may be configured by the HPLMN with a configured NSSAI per PLMN. Upon successful completion of a UE's registration procedure, the UE 100 may obtain from the AMF 155 an Allowed NSSAI for this PLMN, which may include one or more S-NSSAIs.

In an example, the Allowed NSSAI may take precedence over the configured NSSAI for a PLMN. The UE 100 may use the S-NSSAIs in the allowed NSSAI corresponding to a network slice for the subsequent network slice selection related procedures in the serving PLMN.

In an example, the establishment of user plane connectivity to a data network via a network slice instance(s) may comprise: performing a RM procedure to select an AMF 155 that may support the required network slices, establishing one or more PDU sessions to the required data network via the network slice instance(s), and/or the like.

In an example, when a UE 100 registers with a PLMN, if the UE 100 for the PLMN has a configured NSSAI or an allowed NSSAI, the UE 100 may provide to the network in RRC and NAS layer a requested NSSAI comprising the S-NSSAI(s) corresponding to the slice(s) to which the UE 100 attempts to register, a temporary user ID if one was assigned to the UE, and/or the like. The requested NSSAI may be configured-NSSAI, allowed-NSSAI, and/or the like.

In an example, when a UE 100 registers with a PLMN, if for the PLMN the UE 100 has no configured NSSAI or allowed NSSAI, the RAN 105 may route NAS signaling from/to the UE 100 to/from a default AMF 155.

In an example, the network, based on local policies, subscription changes and/or UE 100 mobility, may change the set of permitted network slice(s) to which the UE 100 is registered. In an example, the network may perform the change during a registration procedure or trigger a notification towards the UE 100 of the change of the supported network slices using an RM procedure (which may trigger a registration procedure). The network may provide the UE 100 with a new allowed NSSAI and tracking area list.

In an example, during a registration procedure in a PLMN, in case the network decides that the UE 100 should be served by a different AMF 155 based on network slice(s) aspects, the AMF 155 that first received the registration request may redirect the registration request to another AMF 155 via the RAN 105 or via direct signaling between the initial AMF 155 and the target AMF 155.

In an example, the network operator may provision the UE 100 with network slice selection policy (NSSP). The NSSP may comprise one or more NSSP rules.

In an example, if a UE 100 has one or more PDU sessions established corresponding to a specific S-NSSAI, the UE 100 may route the user data of the application in one of the PDU sessions, unless other conditions in the UE 100 may prohibit the use of the PDU sessions. If the application provides a DNN, then the UE 100 may consider the DNN to determine which PDU session to use. In an example, if the UE 100 does not have a PDU session established with the specific S-NSSAI, the UE 100 may request a new PDU session corresponding to the S-NSSAI and with the DNN that may be provided by the application. In an example, in order for the RAN 105 to select a proper resource for supporting network slicing in the RAN 105, the RAN 105 may be aware of the network slices used by the UE 100.

In an example, an AMF 155 may select an SMF 160 in a network slice instance based on S-NSSAI, DNN and/or other information e.g. UE 100 subscription and local operator policies, and/or the like, when the UE 100 triggers the establishment of a PDU session. The selected SMF 160 may establish the PDU session based on S-NSSAI and DNN.

In an example, in order to support network-controlled privacy of slice information for the slices the UE 100 may access, when the UE 100 is aware or configured that privacy considerations may apply to NSSAI, the UE 100 may not include NSSAI in NAS signaling unless the UE 100 has a NAS security context and the UE 100 may not include NSSAI in unprotected RRC signaling.

In an example, for roaming scenarios, the network slice specific network functions in VPLMN and HPLMN may be selected based on the S-NSSAI provided by the UE 100 during PDU connection establishment. If a standardized S-NSSAI is used, selection of slice specific NF instances may be done by one or more PLMNs based on the provided S-NSSAI. In an example, the VPLMN may map the S-NSSAI of HPLMN to a S-NSSAI of VPLMN based on roaming agreement (e.g., including mapping to a default S-NSSAI of VPLMN). In an example, the selection of slice specific NF instance in VPLMN may be done based on the S-NSSAI of VPLMN. In an example, the selection of any slice specific NF instance in HPLMN may be based on the S-NSSAI of HPLMN.

As depicted in example FIG. 8 and FIG. 9, a registration procedure may be performed by the UE 100 to get authorized to receive services, to enable mobility tracking, to enable reachability, and/or the like.

In an example, the UE 100 may send to the (R)AN 105 an AN message (comprising AN parameters, RM-NAS registration request (registration type, SUCI or SUPI or 5G-GUTI, last visited TAI (if available), security parameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GC capability, PDU session status, PDU session(s) to be re-activated, Follow on request, MICO mode preference, and/or the like), and/or the like). In an example, in case of NG-RAN, the AN parameters may include e.g. SUCI or SUPI or the 5G-GUTI, the Selected PLMN ID and requested NSSAI, and/or the like. In an example, the AN parameters may comprise establishment cause. The establishment cause may provide the reason for requesting the establishment of an RRC connection. In an example, the registration type may indicate if the UE 100 wants to perform an initial registration (i.e. the UE 100 is in RM-DEREGISTERED state), a mobility registration update (e.g., the UE 100 is in RM-REGISTERED state and initiates a registration procedure due to mobility), a periodic registration update (e.g., the UE 100 is in RM-REGISTERED state and may initiate a registration procedure due to the periodic registration update timer expiry) or an emergency registration (e.g., the UE 100 is in limited service state). In an example, if the UE 100 performing an initial registration (i.e., the UE 100 is in RM-DEREGISTERED state) to a PLMN for which the UE 100 does not already have a 5G-GUTI, the UE 100 may include its SUCI or SUPI in the registration request. The SUCI may be included if the home network has provisioned the public key to protect SUPI in the UE. If the UE 100 received a UE 100 configuration update command indicating that the UE 100 needs to re-register and the 5G-GUTI is invalid, the UE 100 may perform an initial registration and may include the SUPI in the registration request message. For an emergency registration, the SUPI may be included if the UE 100 does not have a valid 5G-GUTI available; the PEI may be included when the UE 100 has no SUPI and no valid 5G-GUTI. In other cases, the 5G-GUTI may be included and it may indicate the last serving AMF 155. If the UE 100 is already registered via a non-3GPP access in a PLMN different from the new PLMN (e.g., not the registered PLMN or an equivalent PLMN of the registered PLMN) of the 3GPP access, the UE 100 may not provide over the 3GPP access the 5G-GUTI allocated by the AMF 155 during the registration procedure over the non-3GPP access. If the UE 100 is already registered via a 3GPP access in a PLMN (e.g., the registered PLMN), different from the new PLMN (i.e. not the registered PLMN or an equivalent PLMN of the registered PLMN) of the non-3GPP access, the UE 100 may not provide over the non-3GPP access the 5G-GUTI allocated by the AMF 155 during the registration procedure over the 3GPP access. The UE 100 may provide the UE's usage setting based on its configuration. In case of initial registration or mobility registration update, the UE 100 may include the mapping of requested NSSAI, which may be the mapping of one or more S-NSSAIs of the requested NSSAI to the S-NSSAIs of the configured NSSAI for the HPLMN, to ensure that the network is able to verify whether the S-NSSAI(s) in the requested NSSAI are permitted based on the subscribed S-NSSAIs. If available, the last visited TAI may be included in order to help the AMF 155 produce registration area for the UE. In an example, the security parameters may be used for authentication and integrity protection. requested NSSAI may indicate the network slice selection assistance information. The PDU session status may indicates the previously established PDU sessions in the UE. When the UE 100 is connected to the two AMF 155 belonging to different PLMN via 3GPP access and non-3GPP access then the PDU session status may indicate the established PDU session of the current PLMN in the UE. The PDU session(s) to be re-activated may be included to indicate the PDU session(s) for which the UE 100 may intend to activate UP connections. A PDU session corresponding to a LADN may not be included in the PDU session(s) to be re-activated when the UE 100 is outside the area of availability of the LADN. The follow on request may be included when the UE 100 may have pending uplink signaling and the UE 100 may not include PDU session(s) to be re-activated, or the registration type may indicate the UE 100 may want to perform an emergency registration.

In an example, if a SUPI is included or the 5G-GUTI does not indicate a valid AMF 155, the (R)AN 105, based on (R)AT and requested NSSAI, if available, may select 808 an AMF 155. If UE 100 is in CM-CONNECTED state, the (R)AN 105 may forward the registration request message to the AMF 155 based on the N2 connection of the UE. If the (R)AN 105 may not select an appropriate AMF 155, it may forward the registration request to an AMF 155 which has been configured, in (R)AN 105, to perform AMF 155 selection 808.

In an example, the (R)AN 105 may send to the new AMF 155 an N2 message (comprising: N2 parameters, RM-NAS registration request (registration type, SUPI or 5G-GUTI, last visited TAI (if available), security parameters, requested NSSAI, mapping of requested NSSAI, UE 100 5GC capability, PDU session status, PDU session(s) to be re-activated, follow on request, and MICO mode preference), and/or the like). In an example, when NG-RAN is used, the N2 parameters may comprise the selected PLMN ID, location information, cell identity and the RAT type related to the cell in which the UE 100 is camping. In an example, when NG-RAN is used, the N2 parameters may include the establishment cause.

In an example, the new AMF 155 may send to the old AMF 155 an Namf_Communication_UEContextTransfer (complete registration request). In an example, if the UE's 5G-GUTI was included in the registration request and the serving AMF 155 has changed since last registration procedure, the new AMF 155 may invoke the Namf_Communication_UEContextTransfer service operation on the old AMF 155 including the complete registration request IE, which may be integrity protected, to request the UE's SUPI and MM Context. The old AMF 155 may use the integrity protected complete registration request IE to verify if the context transfer service operation invocation corresponds to the UE 100 requested. In an example, the old AMF 155 may transfer the event subscriptions information by one or more NF consumers, for the UE, to the new AMF 155. In an example, if the UE 100 identifies itself with PEI, the SUPI request may be skipped.

In an example, the old AMF 155 may send to new AMF 155 a response to Namf_Communication_UEContextTransfer (SUPI, MM context, SMF 160 information, PCF ID). In an example, the old AMF 155 may respond to the new AMF 155 for the Namf_Communication_UEContextTransfer invocation by including the UE's SUPI and MM context. In an example, if old AMF 155 holds information about established PDU sessions, the old AMF 155 may include SMF 160 information including S-NSSAI(s), SMF 160 identities and PDU session ID. In an example, if old AMF 155 holds information about active NGAP UE-TNLA bindings to N3IWF, the old AMF 155 may include information about the NGAP UE-TNLA bindings.

In an example, if the SUPI is not provided by the UE 100 nor retrieved from the old AMF 155 the identity request procedure may be initiated by the AMF 155 sending an identity request message to the UE 100 requesting the SUCI.

In an example, the UE 100 may respond with an identity response message including the SUCI. The UE 100 may derive the SUCI by using the provisioned public key of the HPLMN.

In an example, the AMF 155 may decide to initiate UE 100 authentication 825 by invoking an AUSF 150. The AMF 155 may select an AUSF 150 based on SUPI or SUCI. In an example, if the AMF 155 is configured to support emergency registration for unauthenticated SUPIs and the UE 100 indicated registration type emergency registration the AMF 155 may skip the authentication and security setup or the AMF 155 may accept that the authentication may fail and may continue the registration procedure.

In an example, the authentication 830 may be performed by Nudm_UEAuthenticate_Get operation. The AUSF 150 may discover a UDM 140. In case the AMF 155 provided a SUCI to AUSF 150, the AUSF 150 may return the SUPI to AMF 155 after the authentication is successful. In an example, if network slicing is used, the AMF 155 may decide if the registration request needs to be rerouted where the initial AMF 155 refers to the AMF 155. In an example, the AMF 155 may initiate NAS security functions. In an example, upon completion of NAS security function setup, the AMF 155 may initiate NGAP procedure to enable 5G-AN use it for securing procedures with the UE. In an example, the 5G-AN may store the security context and may acknowledge to the AMF 155. The 5G-AN may use the security context to protect the messages exchanged with the UE.

In an example, new AMF 155 may send to the old AMF 155 Namf_Communication_RegistrationCompleteNotify. If the AMF 155 has changed, the new AMF 155 may notify the old AMF 155 that the registration of the UE 100 in the new AMF 155 may be completed by invoking the Namf_Communication_RegistrationCompleteNotify service operation. If the authentication/security procedure fails, then the registration may be rejected, and the new AMF 155 may invoke the Namf_Communication_RegistrationCompleteNotify service operation with a reject indication reason code towards the old AMF 155. The old AMF 155 may continue as if the UE 100 context transfer service operation was never received. If one or more of the S-NSSAIs used in the old registration area may not be served in the target registration area, the new AMF 155 may determine which PDU session may not be supported in the new registration area. The new AMF 155 may invoke the Namf_Communication_RegistrationCompleteNotify service operation including the rejected PDU session ID and a reject cause (e.g. the S-NSSAI becomes no longer available) towards the old AMF 155. The new AMF 155 may modify the PDU session status correspondingly. The old AMF 155 may inform the corresponding SMF 160(s) to locally release the UE's SM context by invoking the Nsmf_PDUSession_ReleaseSMContext service operation.

In an example, the new AMF 155 may send to the UE 100 an identity request/response (e.g., PEI). If the PEI was not provided by the UE 100 nor retrieved from the old AMF 155, the identity request procedure may be initiated by AMF 155 sending an identity request message to the UE 100 to retrieve the PEI. The PEI may be transferred encrypted unless the UE 100 performs emergency registration and may not be authenticated. For an emergency registration, the UE 100 may have included the PEI in the registration request.

In an example, the new AMF 155 may initiate ME identity check by invoking the N5g-eir_EquipmentIdentityCheck_Get service operation.

In an example, the new AMF 155, based on the SUPI, may select 905 a UDM 140. The UDM 140 may select a UDR instance. In an example, the AMF 155 may select a UDM 140.

In an example, if the AMF 155 has changed since the last registration procedure, or if the UE 100 provides a SUPI which may not refer to a valid context in the AMF 155, or if the UE 100 registers to the same AMF 155 it has already registered to a non-3GPP access (e.g., the UE 100 is registered over a non-3GPP access and may initiate the registration procedure to add a 3GPP access), the new AMF 155 may register with the UDM 140 using Nudm_UECM_Registration and may subscribe to be notified when the UDM 140 may deregister the AMF 155. The UDM 140 may store the AMF 155 identity associated to the access type and may not remove the AMF 155 identity associated to the other access type. The UDM 140 may store information provided at registration in UDR, by Nudr_UDM_Update. In an example, the AMF 155 may retrieve the access and mobility subscription data and SMF 160 selection subscription data using Nudm_SDM_Get. The UDM 140 may retrieve this information from UDR by Nudr_UDM_Query(access and mobility subscription data). After a successful response is received, the AMF 155 may subscribe to be notified using Nudm_SDM_Subscribe when the data requested may be modified. The UDM 140 may subscribe to UDR by Nudr_UDM_Subscribe. The GPSI may be provided to the AMF 155 in the subscription data from the UDM 140 if the GPSI is available in the UE 100 subscription data. In an example, the new AMF 155 may provide the access type it serves for the UE 100 to the UDM 140 and the access type may be set to 3GPP access. The UDM 140 may store the associated access type together with the serving AMF 155 in UDR by Nudr_UDM_Update. The new AMF 155 may create an MM context for the UE 100 after getting the mobility subscription data from the UDM 140. In an example, when the UDM 140 stores the associated access type together with the serving AMF 155, the UDM 140 may initiate a Nudm_UECM_DeregistrationNotification to the old AMF 155 corresponding to 3GPP access. The old AMF 155 may remove the MM context of the UE. If the serving NF removal reason indicated by the UDM 140 is initial registration, then the old AMF 155 may invoke the Namf_EventExposure_Notify service operation towards the associated SMF 160 s of the UE 100 to notify that the UE 100 is deregistered from old AMF 155. The SMF 160 may release the PDU session(s) on getting this notification. In an example, the old AMF 155 may unsubscribe with the UDM 140 for subscription data using Nudm_SDM_unsubscribe.

In an example, if the AMF 155 decides to initiate PCF 135 communication, e.g. the AMF 155 has not yet obtained access and mobility policy for the UE 100 or if the access and mobility policy in the AMF 155 are no longer valid, the AMF 155 may select 925 a PCF 135. If the new AMF 155 receives a PCF ID from the old AMF 155 and successfully contacts the PCF 135 identified by the PCF ID, the AMF 155 may select the (V-)PCF identified by the PCF ID. If the PCF 135 identified by the PCF ID may not be used (e.g. no response from the PCF 135) or if there is no PCF ID received from the old AMF 155, the AMF 155 may select 925 a PCF 135.

In an example, the new AMF 155 may perform a policy association establishment during registration procedure. If the new AMF 155 contacts the PCF 135 identified by the (V-) PCF ID received during inter-AMF 155 mobility, the new AMF 155 may include the PCF-ID in the Npcf_AMPolicyControl Get operation. If the AMF 155 notifies the mobility restrictions (e.g. UE 100 location) to the PCF 135 for adjustment, or if the PCF 135 updates the mobility restrictions itself due to some conditions (e.g. application in use, time and date), the PCF 135 may provide the updated mobility restrictions to the AMF 155.

In an example, the PCF 135 may invoke Namf_EventExposure_Subscribe service operation for UE 100 event subscription.

In an example, the AMF 155 may send to the SMF 160 an Nsmf_PDUSession_UpdateSMContext. In an example, the AMF 155 may invoke the Nsmf_PDUSession_UpdateSMContext if the PDU session(s) to be re-activated is included in the registration request. The AMF 155 may send Nsmf_PDUSession_UpdateSMContext request to SMF 160(s) associated with the PDU session(s) to activate user plane connections of the PDU session(s). The SMF 160 may decide to trigger e.g. the intermediate UPF 110 insertion, removal or change of PSA. In the case that the intermediate UPF 110 insertion, removal, or relocation is performed for the PDU session(s) not included in PDU session(s) to be re-activated, the procedure may be performed without N11 and N2 interactions to update the N3 user plane between (R)AN 105 and 5GC. The AMF 155 may invoke the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF 160 if any PDU session status indicates that it is released at the UE 100. The AMF 155 may invoke the Nsmf_PDUSession_ReleaseSMContext service operation towards the SMF 160 in order to release any network resources related to the PDU session.

In an example, the new AMF 155155 may send to a N3IWF an N2 AMF 155 mobility request. If the AMF 155 has changed, the new AMF 155 may create an NGAP UE 100 association towards the N3IWF to which the UE 100 is connected. In an example, the N3IWF may respond to the new AMF 155 with an N2 AMF 155 mobility response.

In an example, the new AMF 155 may send to the UE 100 a registration accept (comprising: 5G-GUTI, registration area, mobility restrictions, PDU session status, allowed NSSAI, [mapping of allowed NSSAI], periodic registration update timer, LADN information and accepted MICO mode, IMS voice over PS session supported indication, emergency service support indicator, and/or the like). In an example, the AMF 155 may send the registration accept message to the UE 100 indicating that the registration request has been accepted. 5G-GUTI may be included if the AMF 155 allocates a new 5G-GUTI. If the AMF 155 allocates a new registration area, it may send the registration area to the UE 100 via registration accept message. If there is no registration area included in the registration accept message, the UE 100 may consider the old registration area as valid. In an example, mobility restrictions may be included in case mobility restrictions may apply for the UE 100 and registration type may not be emergency registration. The AMF 155 may indicate the established PDU sessions to the UE 100 in the PDU session status. The UE 100 may remove locally any internal resources related to PDU sessions that are not marked as established in the received PDU session status. In an example, when the UE 100 is connected to the two AMF 155 belonging to different PLMN via 3GPP access and non-3GPP access then the UE 100 may remove locally any internal resources related to the PDU session of the current PLMN that are not marked as established in received PDU session status. If the PDU session status information was in the registration request, the AMF 155 may indicate the PDU session status to the UE. The mapping of allowed NSSAI may be the mapping of one or more S-NSSAI of the allowed NSSAI to the S-NSSAIs of the configured NSSAI for the HPLMN. The AMF 155 may include in the registration accept message the LADN information for LADNs that are available within the registration area determined by the AMF 155 for the UE. If the UE 100 included MICO mode in the request, then AMF 155 may respond whether MICO mode may be used. The AMF 155 may set the IMS voice over PS session supported Indication. In an example, in order to set the IMS voice over PS session supported indication, the AMF 155 may perform a UE/RAN radio information and compatibility request procedure to check the compatibility of the UE 100 and RAN radio capabilities related to IMS voice over PS. In an example, the emergency service support indicator may inform the UE 100 that emergency services are supported, e.g., the UE 100 may request PDU session for emergency services. In an example, the handover restriction list and UE-AMBR may be provided to NG-RAN by the AMF 155.

In an example, the UE 100 may send to the new AMF 155 a registration complete message. In an example, the UE 100 may send the registration complete message to the AMF 155 to acknowledge that a new 5G-GUTI may be assigned. In an example, when information about the PDU session(s) to be re-activated is not included in the registration request, the AMF 155 may release the signaling connection with the UE 100. In an example, when the follow-on request is included in the registration request, the AMF 155 may not release the signaling connection after the completion of the registration procedure. In an example, if the AMF 155 is aware that some signaling is pending in the AMF 155 or between the UE 100 and the SGC, the AMF 155 may not release the signaling connection after the completion of the registration procedure.

As depicted in example FIG. 10 and FIG. 11, a service request procedure e.g., a UE 100 triggered service request procedure may be used by a UE 100 in CM-IDLE state to request the establishment of a secure connection to an AMF 155. FIG. 11 is continuation of FIG. 10 depicting the service request procedure. The service request procedure may be used to activate a user plane connection for an established PDU session. The service request procedure may be triggered by the UE 100 or the SGC, and may be used when the UE 100 is in CM-IDLE and/or in CM-CONNECTED and may allow selectively to activate user plane connections for some of the established PDU sessions.

In an example, a UE 100 in CM IDLE state may initiate the service request procedure to send uplink signaling messages, user data, and/or the like, as a response to a network paging request, and/or the like. In an example, after receiving the service request message, the AMF 155 may perform authentication. In an example, after the establishment of signaling connection to the AMF 155, the UE 100 or network may send signaling messages, e.g. PDU session establishment from the UE 100 to a SMF 160, via the AMF 155.

In an example, for any service request, the AMF 155 may respond with a service accept message to synchronize PDU session status between the UE 100 and network. The AMF 155 may respond with a service reject message to the UE 100, if the service request may not be accepted by the network. The service reject message may include an indication or cause code requesting the UE 100 to perform a registration update procedure. In an example, for service request due to user data, network may take further actions if user plane connection activation may not be successful. In an example FIG. 10 and FIG. 11, more than one UPF, e.g., old UPF 110-2 and PDU session Anchor PSA UPF 110-3 may be involved.

In an example, the UE 100 may send to a (R)AN 105 an AN message comprising AN parameters, mobility management, MM NAS service request (e.g., list of PDU sessions to be activated, list of allowed PDU sessions, security parameters, PDU session status, and/or the like), and/or the like. In an example, the UE 100 may provide the list of PDU sessions to be activated when the UE 100 may re-activate the PDU session(s). The list of allowed PDU sessions may be provided by the UE 100 when the service request may be a response of a paging or a NAS notification, and may identify the PDU sessions that may be transferred or associated to the access on which the service request may be sent. In an example, for the case of NG-RAN, the AN parameters may include selected PLMN ID, and an establishment cause. The establishment cause may provide the reason for requesting the establishment of an RRC connection. The UE 100 may send NAS service request message towards the AMF 155 encapsulated in an RRC message to the RAN 105.

In an example, if the service request may be triggered for user data, the UE 100 may identify, using the list of PDU sessions to be activated, the PDU session(s) for which the UP connections are to be activated in the NAS service request message. If the service request may be triggered for signaling, the UE 100 may not identify any PDU session(s). If this procedure may be triggered for paging response, and/or the UE 100 may have at the same time user data to be transferred, the UE 100 may identify the PDU session(s) whose UP connections may be activated in MM NAS service request message, by the list of PDU sessions to be activated.

In an example, if the service request over 3GPP access may be triggered in response to a paging indicating non-3GPP access, the NAS service request message may identify in the list of allowed PDU sessions the list of PDU sessions associated with the non-3GPP access that may be re-activated over 3GPP. In an example, the PDU session status may indicate the PDU sessions available in the UE 100. In an example, the UE 100 may not trigger the service request procedure for a PDU session corresponding to a LADN when the UE 100 may be outside the area of availability of the LADN. The UE 100 may not identify such PDU session(s) in the list of PDU sessions to be activated, if the service request may be triggered for other reasons.

In an example, the (R)AN 105 may send to AMF 155 an N2 Message (e.g., a service request) comprising N2 parameters, MM NAS service request, and/or the like. The AMF 155 may reject the N2 message if it may not be able to handle the service request. In an example, if NG-RAN may be used, the N2 parameters may include the 5G-GUTI, selected PLMN ID, location information, RAT type, establishment cause, and/or the like. In an example, the 5G-GUTI may be obtained in RRC procedure and the (R)AN 105 may select the AMF 155 according to the 5G-GUTI. In an example, the location information and RAT type may relate to the cell in which the UE 100 may be camping. In an example, based on the PDU session status, the AMF 155 may initiate PDU session release procedure in the network for the PDU sessions whose PDU session ID(s) may be indicated by the UE 100 as not available.

In an example, if the service request was not sent integrity protected or integrity protection verification failed, the AMF 155 may initiate a NAS authentication/security procedure.

In an example, if the UE 100 triggers the service request to establish a signaling connection, upon successful establishment of the signaling connection, the UE 100 and the network may exchange NAS signaling.

In an example the AMF 155 may send to the SMF 160 a PDU session update context request (e.g., Nsmf_PDUSession_UpdateSMContext request comprising PDU session ID(s), Cause(s), UE 100 location information, access type, and/or the like).

In an example, the Nsmf_PDUSession_UpdateSMContext request may be invoked by the AMF 155 if the UE 100 may identify PDU session(s) to be activated in the NAS service request message. In an example, the Nsmf_PDUSession_UpdateSMContext request may be triggered by the SMF 160 wherein the PDU session(s) identified by the UE 100 may correlate to other PDU session ID(s) than the one triggering the procedure. In an example, the Nsmf_PDUSession_UpdateSMContext request may be triggered by the SMF 160 wherein the current UE 100 location may be outside the area of validity for the N2 information provided by the SMF 160 during a network triggered service request procedure. The AMF 155 may not send the N2 information provided by the SMF 160 during the network triggered service request procedure.

In an example, the AMF 155 may determine the PDU session(s) to be activated and may send an Nsmf_PDUSession_UpdateSMContext request to SMF 160(s) associated with the PDU session(s) with cause set to indicate establishment of user plane resources for the PDU session(s).

In an example, if the procedure may be triggered in response to paging indicating non-3GPP access, and the list of allowed PDU sessions provided by the UE 100 may not include the PDU session for which the UE 100 was paged, the AMF 155 may notify the SMF 160 that the user plane for the PDU session may not be re-activated. The service request procedure may succeed without re-activating the user plane of any PDU sessions, and the AMF 155 may notify the UE 100.

In an example, if the PDU session ID may correspond to a LADN and the SMF 160 may determine that the UE 100 may be outside the area of availability of the LADN based on the UE 100 location reporting from the AMF 155, the SMF 160 may decide to (based on local policies) keep the PDU session, may reject the activation of user plane connection for the PDU session and may inform the AMF 155. In an example, if the procedure may be triggered by a network triggered service request, the SMF 160 may notify the UPF 110 that originated the data notification to discard downlink data for the PDU sessions and/or to not provide further data notification messages. The SMF 160 may respond to the AMF 155 with an appropriate reject cause and the user plane activation of PDU session may be stopped.

In an example, if the PDU session ID may correspond to a LADN and the SMF 160 may determine that the UE 100 may be outside the area of availability of the LADN based on the UE 100 location reporting from the AMF 155, the SMF 160 may decide to (based on local policies) release the PDU session. The SMF 160 may locally release the PDU session and may inform the AMF 155 that the PDU session may be released. The SMF 160 may respond to the AMF 155 with an appropriate reject cause and the user plane Activation of PDU session may be stopped.

In an example, if the UP activation of the PDU session may be accepted by the SMF 160, based on the location info received from the AMF 155, the SMF 160 may check the UPF 110 Selection 1025 Criteria (e.g., UPF's 110 dynamic load, UPF's 110 relative static capacity among UPFs supporting the same DNN, UPF 110 location available at the SMF 160, UE 100 location information, Capability of the UPF 110 and the functionality required for the particular UE 100 session. In an example, an appropriate UPF 110 may be selected by matching the functionality and features required for a UE 100, DNN, PDU session type (i.e. IPv4, IPv6, ethernet type or unstructured type) and if applicable, the static IP address/prefix, SSC mode selected for the PDU session, UE 100 subscription profile in UDM 140, DNAI as included in the PCC rules, local operator policies, S-NSSAI, access technology being used by the UE 100, UPF 110 logical topology, and/or the like), and may determine to perform one or more of the following: continue using the current UPF(s); may select a new intermediate UPF 110 (or add/remove an intermediate UPF 110), if the UE 100 has moved out of the service area of the UPF 110 that was previously connecting to the (R)AN 105, while maintaining the UPF(s) acting as PDU session anchor; may trigger re-establishment of the PDU session to perform relocation/reallocation of the UPF 110 acting as PDU session anchor, e.g. the UE 100 has moved out of the service area of the anchor UPF 110 which is connecting to RAN 105.

In an example, the SMF 160 may send to the UPF 110 (e.g., new intermediate UPF 110) an N4 session establishment request. In an example, if the SMF 160 may select a new UPF 110 to act as intermediate UPF 110-2 for the PDU session, or if the SMF 160 may select to insert an intermediate UPF 110 for a PDU session which may not have an intermediate UPF 110-2, an N4 session establishment request 100 message may be sent to the new UPF 110, providing packet detection, data forwarding, enforcement and reporting rules to be installed on the new intermediate UPF. The PDU session anchor addressing information (on N9) for this PDU session may be provided to the intermediate UPF 110-2.

In an example, if a new UPF 110 is selected by the SMF 160 to replace the old (intermediate) UPF 110-2, the SMF 160 may include a data forwarding indication. The data forwarding indication may indicate to the UPF 110 that a second tunnel endpoint may be reserved for buffered DL data from the old I-UPF.

In an example, the new UPF 110 (intermediate) may send to SMF 160 an N4 session establishment response message. In case the UPF 110 may allocate CN tunnel info, the UPF 110 may provide DL CN tunnel info for the UPF 110 acting as PDU session anchor and UL CN tunnel info (e.g., CN N3 tunnel info) to the SMF 160. If the data forwarding indication may be received, the new (intermediate) UPF 110 acting as N3 terminating point may send DL CN tunnel info for the old (intermediate) UPF 110-2 to the SMF 160. The SMF 160 may start a timer, to release the resource in the old intermediate UPF 110-2.

In an example, if the SMF 160 may select a new intermediate UPF 110 for the PDU session or may remove the old I-UPF 110-2, the SMF 160 may send N4 session modification request message to PDU session anchor, PSA UPF 110-3, providing the data forwarding indication and DL tunnel information from new intermediate UPF 110.

In an example, if the new intermediate UPF 110 may be added for the PDU session, the (PSA) UPF 110-3 may begin to send the DL data to the new I-UPF 110 as indicated in the DL tunnel information.

In an example, if the service request may be triggered by the network, and the SMF 160 may remove the old I-UPF 110-2 and may not replace the old I-UPF 110-2 with the new I-UPF 110, the SMF 160 may include the data forwarding indication in the request. The data forwarding indication may indicate to the (PSA) UPF 110-3 that a second tunnel endpoint may be reserved for buffered DL data from the old I-UPF 110-2. In this case, the PSA UPF 110-3 may begin to buffer the DL data it may receive at the same time from the N6 interface.

In an example, the PSA UPF 110-3 (PSA) may send to the SMF 160 an N4 session modification response. In an example, if the data forwarding indication may be received, the PSA UPF 110-3 may become as N3 terminating point and may send CN DL tunnel info for the old (intermediate) UPF 110-2 to the SMF 160. The SMF 160 may start a timer, to release the resource in old intermediate UPF 110-2 if there is one.

In an example, the SMF 160 may send to the old UPF 110-2 an N4 session modification request (e.g., may comprise new UPF 110 address, new UPF 110 DL tunnel ID, and/or the like). In an example, if the service request may be triggered by the network, and/or the SMF 160 may remove the old (intermediate) UPF 110-2, the SMF 160 may send the N4 session modification request message to the old (intermediate) UPF 110-2, and may provide the DL tunnel information for the buffered DL data. If the SMF 160 may allocate new I-UPF 110, the DL tunnel information is from the new (intermediate) UPF 110 may act as N3 terminating point. If the SMF 160 may not allocate a new I-UPF 110, the DL tunnel information may be from the new UPF 110 (PSA) 110-3 acting as N3 terminating point. The SMF 160 may start a timer to monitor the forwarding tunnel. In an example, the old (intermediate) UPF 110-2 may send N4 session modification response message to the SMF 160.

In an example, if the I-UPF 110-2 may be relocated and forwarding tunnel was established to the new I-UPF 110, the old (intermediate) UPF 110-2 may forward its buffered data to the new (intermediate) UPF 110 acting as N3 terminating point. In an example, if the old I-UPF 110-2 may be removed and the new I-UPF 110 may not be assigned for the PDU session and forwarding tunnel may be established to the UPF 110 (PSA) 110-3, the old (intermediate) UPF 110-2 may forward its buffered data to the UPF 110 (PSA) 110-3 acting as N3 terminating point.

In an example, the SMF 160 may send to the AMF 155 an N11 message e.g., a Nsmf_PDUSession_UpdateSMContext response (comprising: N1 SM container (PDU session ID, PDU session re-establishment indication), N2 SM information (PDU session ID, QoS profile, CN N3 tunnel info, S-NSSAI), Cause), upon reception of the Nsmf_PDUSession_UpdateSMContext request with a cause including e.g., establishment of user plane resources. The SMF 160 may determine whether UPF 110 reallocation may be performed, based on the UE 100 location information, UPF 110 service area and operator policies. In an example, for a PDU session that the SMF 160 may determine to be served by the current UPF 110, e.g., PDU session anchor or intermediate UPF, the SMF 160 may generate N2 SM information and may send an Nsmf_PDUSession_UpdateSMContext response to the AMF 155 to establish the user plane(s). The N2 SM information may contain information that the AMF 155 may provide to the RAN 105. In an example, for a PDU session that the SMF 160 may determine as requiring a UPF 110 relocation for PDU session anchor UPF, the SMF 160 may reject the activation of UP of the PDU session by sending Nsmf_PDUSession_UpdateSMContext response that may contain N1 SM container to the UE 100 via the AMF 155. The N1 SM container may include the corresponding PDU session ID and PDU session re-establishment indication.

Upon reception of the Namf_EventExposure_Notify from the AMF 155 to the SMF 160, with an indication that the UE 100 is reachable, if the SMF 160 may have pending DL data, the SMF 160 may invoke the Namf_Communication_N1N2MessageTransfer service operation to the AMF 155 to establish the user plane(s) for the PDU sessions. In an example, the SMF 160 may resume sending DL data notifications to the AMF 155 in case of DL data.

In an example, the SMF 160 may send a message to the AMF 155 to reject the activation of UP of the PDU session by including a cause in the Nsmf_PDUSession_UpdateSMContext response if the PDU session may correspond to a LADN and the UE 100 may be outside the area of availability of the LADN, or if the AMF 155 may notify the SMF 160 that the UE 100 may be reachable for regulatory prioritized service, and the PDU session to be activated may not for a regulatory prioritized service; or if the SMF 160 may decide to perform PSA UPF 110-3 relocation for the requested PDU session.

In an example, the AMF 155 may send to the (R)AN 105 an N2 request message (e.g., N2 SM information received from SMF 160, security context, AMF 155 signaling connection ID, handover restriction list, MM NAS service accept, list of recommended cells/TAs/NG-RAN node identifiers). In an example, the RAN 105 may store the security context, AMF 155 signaling connection Id, QoS information for the QoS flows of the PDU sessions that may be activated and N3 tunnel IDs in the UE 100 RAN 105 context. In an example, the MM NAS service accept may include PDU session status in the AMF 155. If the activation of UP of a PDU session may be rejected by the SMF 160, the MM NAS service accept may include the PDU session ID and the reason why the user plane resources may not be activated (e.g. LADN not available). Local PDU session release during the session request procedure may be indicated to the UE 100 via the session Status.

In an example, if there are multiple PDU sessions that may involve multiple SMF 160 s, the AMF 155 may not wait for responses from SMF 160 s before it may send N2 SM information to the UE 100. The AMF 155 may wait for responses from the SMF 160 s before it may send MM NAS service accept message to the UE 100.

In an example, the AMF 155 may include at least one N2 SM information from the SMF 160 if the procedure may be triggered for PDU session user plane activation. AMF 155 may send additional N2 SM information from SMF 160 s in separate N2 message(s) (e.g. N2 tunnel setup request), if there is any. Alternatively, if multiple SMF 160 s may be involved, the AMF 155 may send one N2 request message to (R)AN 105 after the Nsmf_PDUSession_UpdateSMContext response service operations from the SMFs 160 associated with the UE 100 may be received. In such case, the N2 request message may include the N2 SM information received in one or more of the Nsmf_PDUSession_UpdateSMContext response and PDU session ID to enable AMF 155 to associate responses to relevant SMF 160.

In an example, if the RAN 105 (e.g., NG RAN) node may provide the list of recommended cells/TAs/NG-RAN node identifiers during the AN release procedure, the AMF 155 may include the information from the list in the N2 request. The RAN 105 may use this information to allocate the RAN 105 notification area when the RAN 105 may decide to enable RRC inactive state for the UE 100.

If the AMF 155 may receive an indication, from the SMF 160 during a PDU session establishment procedure that the UE 100 may be using a PDU session related to latency sensitive services, for any of the PDU sessions established for the UE 100 and the AMF 155 has received an indication from the UE 100 that may support the CM-CONNECTED with RRC inactive state, then the AMF 155 may include the UE's RRC inactive assistance information. In an example, the AMF 155 based on network configuration, may include the UE's RRC inactive assistance information.

In an example, the (R)AN 105 may send to the UE 100 a message to perform RRC connection reconfiguration with the UE 100 depending on the QoS information for the QoS flows of the PDU sessions whose UP connections may be activated and data radio bearers. In an example, the user plane security may be established.

In an example, if the N2 request may include a MM NAS service accept message, the RAN 105 may forward the MM NAS service accept to the UE 100. The UE 100 may locally delete context of PDU sessions that may not be available in 5GC.

In an example, if the N1 SM information may be transmitted to the UE 100 and may indicate that some PDU session(s) may be re-established, the UE 100 may initiate PDU session re-establishment for the PDU session(s) that may be re-established after the service request procedure may be complete.

In an example, after the user plane radio resources may be setup, the uplink data from the UE 100 may be forwarded to the RAN 105. The RAN 105 (e.g., NG-RAN) may send the uplink data to the UPF 110 address and tunnel ID provided.

In an example, the (R)AN 105 may send to the AMF 155 an N2 request Ack (e.g., N2 SM information (comprising: AN tunnel info, list of accepted QoS flows for the PDU sessions whose UP connections are activated, list of rejected QoS flows for the PDU sessions whose UP connections are activated)). In an example, the N2 request message may include N2 SM information(s), e.g. AN tunnel info. RAN 105 may respond N2 SM information with separate N2 message (e.g. N2 tunnel setup response). In an example, if multiple N2 SM information are included in the N2 request message, the N2 request Ack may include multiple N2 SM information and information to enable the AMF 155 to associate the responses to relevant SMF 160.

In an example, the AMF 155 may send to the SMF 160 a Nsmf_PDUSession_UpdateSMContext request (N2 SM information (AN tunnel info), RAT type) per PDU session. If the AMF 155 may receive N2 SM information (one or multiple) from the RAN 105, then the AMF 155 may forward the N2 SM information to the relevant SMF 160. If the UE 100 time zone may change compared to the last reported UE 100 Time Zone then the AMF 155 may include the UE 100 time zone IE in the Nsmf_PDUSession_UpdateSMContext request message.

In an example, if dynamic PCC is deployed, the SMF 160 may initiate notification about new location information to the PCF 135 (if subscribed) by invoking an event exposure notification operation (e.g., a Nsmf_EventExposure_Notify service operation). The PCF 135 may provide updated policies by invoking a policy control update notification message (e.g., a Npcf_SMPolicyControl_UpdateNotify operation).

In an example, if the SMF 160 may select a new UPF 110 to act as intermediate UPF 110 for the PDU session, the SMF 160 may initiates an N4 session modification procedure to the new I-UPF 110 and may provide AN tunnel info. The downlink data from the new I-UPF 110 may be forwarded to RAN 105 and UE 100. In an example, the UPF 110 may send to the SMF 160, an N4 session modification response. In an example, the SMF 160 may send to the AMF 155, an Nsmf_PDUSession_UpdateSMContext response.

In an example, if forwarding tunnel may be established to the new I-UPF 110 and if the timer SMF 160 set for forwarding tunnel may be expired, the SMF 160 may sends N4 session modification request to new (intermediate) UPF 110 acting as N3 terminating point to release the forwarding tunnel. In an example, the new (intermediate) UPF 110 may send to the SMF 160 an N4 session modification response. In an example, the SMF 160 may send to the PSA UPF 110-3 an N4 session modification request, or N4 session release request. In an example, if the SMF 160 may continue using the old UPF 110-2, the SMF 160 may send an N4 session modification request, providing AN tunnel info. In an example, if the SMF 160 may select a new UPF 110 to act as intermediate UPF 110, and the old UPF 110-2 may not be PSA UPF 110-3, the SMF 160 may initiate resource release, after timer expires, by sending an N4 session release request (release cause) to the old intermediate UPF 110-2.

In an example, the old intermediate UPF 110-2 may send to the SMF 160 an N4 session modification response or N4 session release response. The old UPF 110-2 may acknowledge with the N4 session modification response or N4 session release response message to confirm the modification or release of resources. The AMF 155 may invoke the Namf_EventExposure_Notify service operation to notify the mobility related events, after this procedure may complete, towards the NFs that may have subscribed for the events. In an example, the AMF 155 may invoke the Namf_EventExposure_Notify towards the SMF 160 if the SMF 160 had subscribed for UE 100 moving into or out of area of interest and if the UE's current location may indicate that it may be moving into or moving outside of the area of interest subscribed, or if the SMF 160 had subscribed for LADN DNN and if the UE 100 may be moving into or outside of an area where the LADN is available, or if the UE 100 may be in MICO mode and the AMF 155 had notified an SMF 160 of the UE 100 being unreachable and that SMF 160 may not send DL data notifications to the AMF 155, and the AMF 155 may informs the SMF 160 that the UE 100 is reachable, or if the SMF 160 had subscribed for UE 100 reachability status, then the AMF 155 may notify the UE 100 reachability.

An example PDU session establishment procedure depicted in FIG. 12 and FIG. 13. In an example embodiment, when the PDU session establishment procedure may be employed, the UE 100 may send to the AMF 155 a NAS Message (or a SM NAS message) comprising NSSAI, S-NSSAI (e.g., requested S-NSSAI, allowed S-NSSAI, subscribed S-NSSAI, and/or the like), DNN, PDU session ID, request type, old PDU session ID, N1 SM container (PDU session establishment request), and/or the like. In an example, the UE 100, in order to establish a new PDU session, may generate a new PDU session ID. In an example, when emergency service may be required and an emergency PDU session may not already be established, the UE 100 may initiate the UE 100 requested PDU session establishment procedure with a request type indicating emergency request. In an example, the UE 100 may initiate the UE 100 requested PDU session establishment procedure by the transmission of the NAS message containing a PDU session establishment request within the N1 SM container. The PDU session establishment request may include a PDU type, SSC mode, protocol configuration options, and/or the like. In an example, the request type may indicate initial request if the PDU session establishment is a request to establish the new PDU session and may indicate existing PDU session if the request refers to an existing PDU session between 3GPP access and non-3GPP access or to an existing PDN connection in EPC. In an example, the request type may indicate emergency request if the PDU session establishment may be a request to establish a PDU session for emergency services. The request type may indicate existing emergency PDU session if the request refers to an existing PDU session for emergency services between 3GPP access and non-3GPP access. In an example, the NAS message sent by the UE 100 may be encapsulated by the AN in a N2 message towards the AMF 155 that may include user location information and access technology type information. In an example, the PDU session establishment request message may contain SM PDU DN request container containing information for the PDU session authorization by the external DN. In an example, if the procedure may be triggered for SSC mode 3 operation, the UE 100 may include the old PDU session ID which may indicate the PDU session ID of the on-going PDU session to be released, in the NAS message. The old PDU session ID may be an optional parameter which may be included in this case. In an example, the AMF 155 may receive from the AN the NAS message (e.g., NAS SM message) together with user location information (e.g. cell ID in case of the RAN 105). In an example, the UE 100 may not trigger a PDU session establishment for a PDU session corresponding to a LADN when the UE 100 is outside the area of availability of the LADN.

In an example, the AMF 155 may determine that the NAS message or the SM NAS message may correspond to the request for the new PDU session based on that request type indicates initial request and that the PDU session ID may not be used for any existing PDU session(s) of the UE 100. If the NAS message does not contain an S-NSSAI, the AMF 155 may determine a default S-NSSAI for the requested PDU session either according to the UE 100 subscription, if it may contain only one default S-NSSAI, or based on operator policy. In an example, the AMF 155 may perform SMF 160 selection 1210 and select an SMF 160. If the request type may indicate initial request or the request may be due to handover from EPS, the AMF 155 may store an association of the S-NSSAI, the PDU session ID and a SMF 160 ID. In an example, if the request type is initial request and if the old PDU session ID indicating the existing PDU session may be contained in the message, the AMF 155 may select the SMF 160 and may store an association of the new PDU session ID and the selected SMF 160 ID.

In an example, the AMF 155 may send to the SMF 160, an N11 message, e.g., Nsmf_PDUSession_CreateSMContext request (comprising: SUPI or PEI, DNN, S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container (PDU session establishment request), user location information, access type, PEI, GPSI), or Nsmf_PDUSession_UpdateSMContext request (SUPI, DNN, S-NSSAI, PDU session ID, AMF 155 ID, request type, N1 SM container (PDU session establishment request), user location information, access type, RAT type, PEI). In an example, if the AMF 155 may not have an association with the SMF 160 for the PDU session ID provided by the UE 100 (e.g. when request type indicates initial request), the AMF 155 may invoke the Nsmf_PDUSession_CreateSMContext request, but if the AMF 155 already has an association with an SMF 160 for the PDU session ID provided by the UE 100 (e.g. when request type indicates existing PDU session), the AMF 155 may invoke the Nsmf_PDUSession_UpdateSMContext request. In an example, the AMF 155 ID may be the UE's GUAMI which uniquely identifies the AMF 155 serving the UE 100. The AMF 155 may forward the PDU session ID together with the N1 SM container containing the PDU session establishment request received from the UE 100. The AMF 155 may provide the PEI instead of the SUPI when the UE 100 has registered for emergency services without providing the SUPI. In case the UE 100 has registered for emergency services but has not been authenticated, the AMF 155 may indicate that the SUPI has not been authenticated.

In an example, if the request type may indicate neither emergency request nor existing emergency PDU session and, if the SMF 160 has not yet registered and subscription data may not be available, the SMF 160 may register with the UDM 140, and may retrieve subscription data 1225 and subscribes to be notified when subscription data may be modified. In an example, if the request type may indicate existing PDU session or existing emergency PDU session, the SMF 160 may determine that the request may be due to handover between 3GPP access and non-3GPP access or due to handover from EPS. The SMF 160 may identify the existing PDU session based on the PDU session ID. The SMF 160 may not create a new SM context but instead may update the existing SM context and may provide the representation of the updated SM context to the AMF 155 in the response. if the request type may be initial request and if the old PDU session ID may be included in Nsmf_PDUSession_CreateSMContext request, the SMF 160 may identify the existing PDU session to be released based on the old PDU session ID.

In an example, the SMF 160 may send to the AMF 155, the N11 message response, e.g., either a PDU session create/update response, Nsmf_PDUSession_CreateSMContext response (cause, SM context ID or N1 SM container (PDU session reject(cause))) or an Nsmf_PDUSession_UpdateSMContext response.

In an example, if the SMF 160 may perform secondary authorization/authentication 1230 during the establishment of the PDU session by a DN-AAA server, the SMF 160 may select a UPF 110 and may trigger a PDU session establishment authentication/authorization.

In an example, if the request type may indicate initial request, the SMF 160 may select an SSC mode for the PDU session. The SMF 160 may select one or more UPFs as needed. In case of PDU type IPv4 or IPv6, the SMF 160 may allocate an IP address/prefix for the PDU session. In case of PDU type IPv6, the SMF 160 may allocate an interface identifier to the UE 100 for the UE 100 to build its link-local address. For Unstructured PDU type the SMF 160 may allocate an IPv6 prefix for the PDU session and N6 point-to-point tunneling (based on UDP/IPv6).

In an example, if dynamic PCC is deployed, the may SMF 160 performs PCF 135 selection 1235. If the request type indicates existing PDU session or existing emergency PDU session, the SMF 160 may use the PCF 135 already selected for the PDU session. If dynamic PCC is not deployed, the SMF 160 may apply local policy.

In an example, the SMF 160 may perform a session management policy establishment procedure to establish a PDU session with the PCF 135 and may get the default PCC Rules for the PDU session. The GPSI may be included if available at the SMF 160. If the request type in 1215 indicates existing PDU session, the SMF 160 may notify an event previously subscribed by the PCF 135 by a session management policy modification procedure and the PCF 135 may update policy information in the SMF 160. The PCF 135 may provide authorized session-AMBR and the authorized 5QI and ARP to SMF 160. The PCF 135 may subscribe to the IP allocation/release event in the SMF 160 (and may subscribe other events).

In an example, the PCF 135, based on the emergency DNN, may set the ARP of the PCC rules to a value that may be reserved for emergency services.

In an example, if the request type in 1215 indicates initial request, the SMF 160 may select an SSC mode for the PDU session. The SMF 160 may select 1245 one or more UPFs as needed. In case of PDU type IPv4 or IPv6, the SMF 160 may allocate an IP address/prefix for the PDU session. In case of PDU type IPv6, the SMF 160 may allocate an interface identifier to the UE 100 for the UE 100 to build its link-local address. For unstructured PDU type the SMF 160 may allocate an IPv6 prefix for the PDU session and N6 point-to-point tunneling (e.g., based on UDP/IPv6). In an example, for Ethernet PDU type PDU session, neither a MAC nor an IP address may be allocated by the SMF 160 to the UE 100 for this PDU session.

In an example, if the request type in 1215 is existing PDU session, the SMF 160 may maintain the same IP address/prefix that may be allocated to the UE 100 in the source network.

In an example, if the request type in 1215 indicates existing PDU session referring to an existing PDU session moved between 3GPP access and non-3GPP access, the SMF 160 may maintain the SSC mode of the PDU session, e.g., the current PDU session Anchor and IP address. In an example, the SMF 160 may trigger e.g. new intermediate UPF 110 insertion or allocation of a new UPF 110. In an example, if the request type indicates emergency request, the SMF 160 may select 1245 the UPF 110 and may select SSC mode 1.

In an example, the SMF 160 may perform a session management policy modification 1250 procedure to report some event to the PCF 135 that has previously subscribed. If request type is initial request and dynamic PCC is deployed and PDU type is IPv4 or IPv6, the SMF 160 may notify the PCF 135 (that has previously subscribed) with the allocated UE 100 IP address/prefix.

In an example, the PCF 135 may provide updated policies to the SMF 160. The PCF 135 may provide authorized session-AMBR and the authorized 5QI and ARP to the SMF 160.

In an example, if request type indicates initial request, the SMF 160 may initiate an N4 session establishment procedure with the selected UPF 110. The SMF 160 may initiate an N4 session modification procedure with the selected UPF 110. In an example, the SMF 160 may send an N4 session establishment/modification request to the UPF 110 and may provide packet detection, enforcement, reporting rules, and/or the like to be installed on the UPF 110 for this PDU session. If CN tunnel info is allocated by the SMF 160, the CN tunnel info may be provided to the UPF 110. If the selective user plane deactivation is required for this PDU session, the SMF 160 may determine the Inactivity Timer and may provide it to the UPF 110. In an example, the UPF 110 may acknowledges by sending an N4 session establishment/modification response. If CN tunnel info is allocated by the UPF, the CN tunnel info may be provided to SMF 160. In an example, if multiple UPFs are selected for the PDU session, the SMF 160 may initiate N4 session establishment/modification procedure with one or more UPFs 110 of the PDU session.

In an example, the SMF 160 may send to the AMF 155 an Namf_Communication_N1N2MessageTransfer message (comprising PDU session ID, access type, N2 SM information (PDU session ID, QFI(s), QoS profile(s), CN tunnel info, S-NSSAI, session-AMBR, PDU session type, and/or the like), N1 SM container (PDU session establishment accept (QoS Rule(s), selected SSC mode, S-NSSAI, allocated IPv4 address, interface identifier, session-AMBR, selected PDU session type, and/or the like))). In case of multiple UPFs are used for the PDU session, the CN tunnel info may comprise tunnel information related with the UPF 110 that terminates N3. In an example, the N2 SM information may carry information that the AMF 155 may forward to the (R)AN 105 (e.g., the CN tunnel info corresponding to the core network address of the N3 tunnel corresponding to the PDU session, one or multiple QoS profiles and the corresponding QFIs may be provided to the (R)AN 105, the PDU session ID may be used by AN signaling with the UE 100 to indicate to the UE 100 the association between AN resources and a PDU session for the UE 100, and/or the like). In an example, a PDU session may be associated to an S-NSSAI and a DNN. In an example, the N1 SM container may contain the PDU session establishment accept that the AMF 155 may provide to the UE 100. In an example, multiple QoS rules and QoS profiles may be included in the PDU session establishment accept within the N1 SM and in the N2 SM information. In an example, the Namf_Communication_N1N2MessageTransfer may further comprise the PDU session ID and information allowing the AMF 155 to know which access towards the UE 100 to use.

In an example, the AMF 155 may send to the (R)AN 105 an N2 PDU session request (comprising N2 SM information, NAS message (PDU session ID, N1 SM container (PDU session establishment accept, and/or the like))). In an example, the AMF 155 may send the NAS message that may comprise PDU session ID and PDU session establishment accept targeted to the UE 100 and the N2 SM information received from the SMF 160 within the N2 PDU session request to the (R)AN 105.

In an example, the (R)AN 105 may issue AN specific signaling exchange with the UE 100 that may be related with the information received from SMF 160. In an example, in case of a 3GPP RAN 105, an RRC connection reconfiguration procedure may take place with the UE 100 to establish the necessary RAN 105 resources related to the QoS Rules for the PDU session request. In an example, (R)AN 105 may allocate (R)AN 105 N3 tunnel information for the PDU session. In case of dual connectivity, the master RAN 105 node may assign some (zero or more) QFIs to be setup to a master RAN 105 node and others to the secondary RAN 105 node. The AN tunnel info may comprise a tunnel endpoint for one or more involved RAN 105 nodes, and the QFIs assigned to one or more tunnel endpoints. A QFI may be assigned to either the master RAN 105 node or the secondary RAN 105 node. In an example, (R)AN 105 may forward the NAS message (PDU session ID, N1 SM container (PDU session establishment accept)) to the UE 100. The (R)AN 105 may provide the NAS message to the UE 100 if the necessary RAN 105 resources are established and the allocation of (R)AN 105 tunnel information are successful.

In an example, the N2 PDU session response may comprise a PDU session ID, cause, N2 SM information (PDU session ID, AN tunnel info, list of accepted/rejected QFI(s)), and/or the like. In an example, the AN tunnel info may correspond to the access network address of the N3 tunnel corresponding to the PDU session.

In an example, the AMF 155 may forward the N2 SM information received from (R)AN 105 to the SMF 160 via a Nsmf_PDUSession_UpdateSMContext request (comprising: N2 SM information, request type, and/or the like). In an example, if the list of rejected QFI(s) is included in N2 SM information, the SMF 160 may release the rejected QFI(s) associated QoS profiles.

In an example, the SMF 160 may initiate an N4 session modification procedure with the UPF 110. The SMF 160 may provide AN tunnel info to the UPF 110 as well as the corresponding forwarding rules. In an example, the UPF 110 may provide an N4 session modification response to the SMF 160.

In an example, the SMF 160 may send to the AMF 155 an Nsmf_PDUSession_UpdateSMContext response (Cause). In an example, the SMF 160 may subscribe to the UE 100 mobility event notification from the AMF 155 (e.g. location reporting, UE 100 moving into or out of area of interest), after this step by invoking Namf_EventExposure_Subscribe service operation. For LADN, the SMF 160 may subscribe to the UE 100 moving into or out of LADN service area event notification by providing the LADN DNN as an indicator for the area of interest. The AMF 155 may forward relevant events subscribed by the SMF 160.

In an example, the SMF 160 may send to the AMF 155, a Nsmf_PDUSession_SMContextStatusNotify (release). In an example, if during the procedure, any time the PDU session establishment is not successful, the SMF 160 may inform the AMF 155 by invoking Nsmf_PDUSession_SMContextStatusNotify(release). The SMF 160 may releases any N4 session(s) created, any PDU session address if allocated (e.g. IP address) and may release the association with the PCF 135.

In an example, in case of PDU type IPv6, the SMF 160 may generate an IPv6 Router Advertisement and may send it to the UE 100 via N4 and the UPF 110.

In an example, if the PDU session may not be established, the SMF 160 may unsubscribe to the modifications of session management subscription data for the corresponding (SUPI, DNN, S-NSSAI), using Nudm_SDM_Unsubscribe (SUPI, DNN, S-NSSAI), if the SMF 160 is no more handling a PDU session of the UE 100 for this (DNN, S-NSSAI). In an example, if the PDU session may not be established, the SMF 160 may deregister for the given PDU session using Nudm_UECM_Deregistration (SUPI, DNN, PDU session ID).

The 5G system may support CIoT and/or MTC capabilities to support frequent small data transmission, infrequent small data transmission. The small data may comprise data payload in the range of e.g., 10, 20, 100 bytes or e.g., 1, 10, 20, 100(s) of kilo bytes.

In an example, CIoT features may support infrequent small data transmissions for at least low complexity, power constrained, low data rate CIoT UEs, and/or the like. In an example, the devices (e.g. utility meters, sensors, low power devices, and/or the like) may be mobile throughout their lifetime.

The end-to-end communications between the CIoT/MTC application in the UE and the CIoT/MTC application in the external network, may utilize services provided by the 3GPP system (e.g., 5GS). In an example, a capability server (e.g., a service capability server, SCS, and/or the like) may provide the end-to-end communications between the CIoT/MTC application in the UE and the CIoT/MTC application in the external network.

The CIoT/MTC application in the external network may be hosted by an application server (AS), an application function (AF) and/or the like. In an example, the AS and/or the AF may employ an SCS for additional value added services. The 3GPP system may provide transport, subscriber management and other communication services including various architectural enhancements, device triggering via control plane/user plane, data transmission via control plane/user plane, and/or the like.

In an example, device triggering may enable the capability server (e.g., SCS) to send information to the UE via the 3GPP network to trigger the UE to perform application specific actions. In an example, the application specific actions may comprise initiating communication with the SCS via the control plane, and/or user plane. Device triggering may be required when an IP address for the UE is not available or reachable by the SCS/AS, or AF.

A device trigger message may comprise information that may enable the network to route the message to the appropriate UE and the UE to route the message to the appropriate application. In an example, a trigger payload may comprise the information destined to the application, the information to route the information, and/or the like. In an example, the trigger payload, upon the reception by the UE may provide information to the application that may trigger application related actions. The application in the UE may perform indicated actions, such as for example to initiate immediate or later communication to the SCS/AS and/or AF, based on the information contained in the trigger payload.

In an example, device triggering may be subscription based. The subscription may provide the information whether a UE is allowed to be triggered by a specific SCS, SCS/AS, AF, and/or the like. In an example, when device triggers are delivered via MT-SMS the serving nodes (e.g., AMF, SMF, UPF, and/or the like) may provide the service towards a specific UE based on the UE's subscription for MT-SMS and other subscription parameters affecting MT-SMS service provision.

In an example, device triggering recall/replace functionality may allow a SCS, SCS/AS, or AF to recall or replace submitted trigger message(s) which are not yet delivered to the UE.

In an example, the 5GS may support functions for high latency communication, HLC. HLC may be used to handle mobile terminated (MT) communication with UEs being unreachable while using power saving functions e.g. UE power saving mode or extended idle mode DRX depending on operator configuration. High latency may be the initial response time before normal exchange of packets is established. The initial response time may be the time it takes before a UE has woken up from its power saving state and responded to the initial downlink packet(s).

In an example, high latency communication may be handled by an extended buffering of downlink data in a UPF, NEF, SMF, AMF, and/or the like. In an example, extended buffering may be controlled by the AMF, SMF, and/or the like. The AMF and/or the SMF may ask the UPF to buffer downlink data until the UE is expected to wake up from its power saving state.

In an example, if control plane CIoT optimization is used, high latency communication may be handled by the buffering of downlink data in the UPF, AMF, SMF and/or the like.

In an example, high latency communication may be handled by notification procedures. The SCS/AS or AF may request notification when a UE wakes up from its power saving state and sends downlink data to the UE when the UE is reachable. In an example, the notification procedure may be available based on monitoring event for UE reachability, monitoring event for availability after data notification (e.g., DDN) failure, and/or the like.

In an example, the SCS/AS or AF may request a one-time UE reachability notification when it wants to send data to the UE. In an example, the SCS/AS or AF may request repeated availability after DDN failure notifications where each notification is triggered by a DDN failure i.e. the SCS/AS may send a downlink packet which is discarded by a core network node (e.g., UPF, SMF, AMF) and may trigger the AMF or SMF to send an event notification to the SCS/AS next time the UE wakes up.

In an example, the length of the power saving intervals used by the network may determine the maximum latency for a UE. An SCS/AS or AF, which has a specific requirement on the maximum latency for UEs it communicates with, may provide its maximum latency requirement to the network.

In an example embodiment, a reachability procedure may be employed to reach a UE. Elements of the reachability procedure may be used by services such as SMS over NAS, data transmission for UEs in power saving mode, and/or the like. The reachability procedure may be employed by UEs that are in RRC-IDLE, RRC-INACTIVE or RRC-CONNECTED states.

In an example embodiment as depicted in example FIG. 14, a UE reachability notification procedure may be employed.

In an example, during a registration or subscription update procedure, a UDM may inform an AMF of the identities (e.g. FQDNs, NF ID, and/or the like) of the network functions (NF) that are authorized to request notifications on the reachability of the UE via a registration service procedure such as Nudm_UECM_Registration, Nudm_SubscriberData_Update service operation, and/or the like.

In an example, if a service-related entity requests the UDM to provide an indication regarding UE reachability, the UDM may check that the service-related entity is authorized to perform this request on the subscriber associated to the UE. In an example, if the entity is not authorized, the request may be rejected (e.g. if the requesting entity is recognized as being a valid entity, but not authorized for that subscriber) or silently discarded (e.g. if the requesting entity is not recognized).

In an example, the UDM may store the identity of the service-related entity and may set the URRP-AMF parameter to indicate that such request is received. If the value of URRP-AMF parameter has changed from “not set” to “set”, the UDM may initiate Namf_EventExposure_Subscribe_service operation (URRP-AMF) towards the AMF. The UDM may indicate if direct notification to the NF may be used. In an example, the UDM may trigger UE reachability notification request procedure with two different AMFs for the UE which may be connected to 5G core network over 3GPP access and non-3GPP access simultaneously. In an example, the UDM may trigger UE reachability notification request procedure with a mobility management entity, MME.

In an example, the AMF may check that the requesting entity is authorized to perform the request on the subscriber. In an example, if the entity is not authorized, the request may be rejected (e.g. if the requesting entity is recognized as being a valid entity, but not authorized for the subscriber) or silently discarded (e.g. if the requesting entity is not recognized).

In an example, if the AMF has a MM Context for the user or the UE, the AMF may set URRP-AMF to indicate the need to report to the UDM information regarding changes in UE reachability, e.g. when the next NAS activity with that UE is detected.

In an example, if the UE state in the AMF is CM-CONNECTED state, the AMF may initiate N2 notification procedure with reporting type set to single RRC-Connected state notification.

In an example embodiment as depicted in example FIG. 15, a UE activity notification procedure may be employed for reachability of a UE.

In an example, an AMF may receive an (N1) NAS signaling for a UE in CM-IDLE that may imply UE reachability, e.g. a registration request or service request message from the UE. In an example, AMF may receive an (N2) UE Notification or an (N2) Path Switch Request from the RAN for a UE in CM-CONNECTED state.

In an example, if the AMF has a MM context for the UE and the URRP-AMF is set to report once that the UE is reachable, the AMF may initiate a notification e.g., an Namf_EventExposure_Notify service operation (e.g., comprising SUPI, UE-Reachable, and/or the like) message to the UDM or directly to the NF (if previously indicated to the AMF). The AMF may clear the corresponding URRP-AMF for the UE.

In an example, when the UDM receives the Namf_EventExposure_Notify service operation (SUPI, UE-Reachable) message or Nudm_UECM_Registration service for a UE that has URRP-AMF set, the UDM may trigger appropriate notifications to the NFs (e.g. SMSF or SMS-GMSC, NEF, and/or the like) that have subscribed to the UDM for the reachability notification.

In an example embodiment, 5GS may support small data communication using an application programming interface (API) corresponding to e.g., T8 API, Nm API, and/or the like. The API may support packet transmission using IP-based, non-IP based, and/or the like protocols on the southbound interface. A messaging function entity (e.g., a network IoT messaging function, NIMF) may be employed. The NIMF may be an extension with an additional role for the 5G network exposure function (NEF), or it may be a new network function dedicated for small data communication for IoT/CIoT. In an example, the NIMF may be a new standalone network function entity.

The NIMF or NEF for small data communication may be located in the operator domain.

In an example, the NIMF may support a northbound Nm interface. On the northbound interface, the Small data network function may support for example the T8 non-IP data delivery NIDD Nm API, unstructured Nm API, and/or the like.

In an example, the NIMF may support a southbound N6m interface. The southbound interface may enable small data communication with different types of CIoT devices using different protocol stacks. In an example, the southbound interface has a PDU session layer which may support PDU Sessions of different types e.g., IPv4, IPv6, Ethernet, unstructured, non-IP, and/or the like. In an example, on top of the PDU session layer higher layer IoT protocols may be employed and supported towards the UE, e.g. Lightweight machine to machine, LWM2M, non-IP data delivery reliable data service, NIDD RDS, and/or the like.

The NIMF or NEF may store and forward small data. The southbound protocols may be terminated in the NIMF or NEF. The NIMF may map or act as proxies between the northbound and southbound protocols.

In an example, the NIMF may support lawful intercept LI (message based), charging (message based, i.e. number of CIoT messages), and/or the like.

In an example, if encryption protocols (e.g., datagram transport layer security (DTLS)) are employed as part of the southbound interface/connection, the NIMF may offer LI of unencrypted data.

In an example, when a UE establishes a PDU Session, as part of the registration procedure, or attach procedure, for which DNN configuration indicates small data communication to be used, then the SMF may initiate a connection towards the NEF or NIMF corresponding to the NEF ID or NIMF ID for the DNN.

In an example as depicted in example FIG. 16, the UE may request the establishment of a PDU Session wherein an N4 session establishment in the UPF may be performed as part of the PDU session establishment.

In an example FIG. 16, the SMF and the UPF may handshake their support for small data communication in a PFCP association setup. The UE may request the establishment of a PDU session. The SMF may determine based on e.g. DNN or local DNN configuration, that the PDU session may be used for small data communication. The SMF may select a UPF for small data communication for the UE and based on UE subscription information. The SMF may send PFCP session establishment request to the selected UPF. The SMF may include a usage reporting rule to invoke message based reporting.

The SMF may send a PFCP small data messaging request (F-SEID) message to the UPF providing additional information for the small data communication. The information may comprise F-SEID (to identify the related PDU session), IMSI, external identifier(s), MSISDN, UE IP address, PDU session type, PDU session ID, serving PLMN rate control, PCO parameters, serving PLMN ID, IMEISV, and/or the like.

The UPF-NEF may store the received information and may acknowledge to the SMF that small data communication with NIDD API towards AF (i.e. SCS/AS) has been established.

UL and DL small data transmissions may take place using IP data or Unstructured (Non-IP) data depending on the PDU session type used by the UE. Higher layer protocols to employ may be decided by application layer interactions between UE and NEF/NIMF or by DN configuration. Examples of higher layer protocols may comprise Lightweight M2M, CoAP, MQTT, DTLS, HTTP, HTTP/2, XMPP, AMQP, Reliable Data Service (RDS), LoRA, and/or the like. In an example, PDU session deletion may be initiated and the PDU session and the small data messaging context may be released in the UPF.

In an example FIG. 16, a connection may be established between the UPF and the NEF/NIMF for the PDU Session. The NEF/NIMF may store the IP address of the PDU Session, the IMSI and the External ID or MSISDN of the UE, the IP version to use (IPv6, IPv4 or Unstructured), and PCO. In an example, for unstructured PDU session when point-to-point tunneling based on UDP/IP encapsulation is used, the UPF may store the forwarding IP address to the selected NIMF. For PDU sessions of type IP, the forwarding to the NIMF may be controlled by IP destination address used at the higher layer protocol (e.g., LWM2M).

In an example, uplink and downlink data transmissions may take place using IP data or Unstructured (Non-IP) data depending on the PDU Session type used by the UE.

In an example, when PDU Session release is initiated, the connection between the UPF and the NIMF may be released. The NIMF may remove the stored IP address of the PDU session, and may mark the UE as inactive, and may close the connection for (small) data transmissions to/from the UE. The N4 Session may be released in the UPF.

In an example embodiment as depicted in example FIG. 17, the 5GS may support unstructured data transmission or non-IP data transmission (NIDD). The UE may support a NIDD client, for delivery of Unstructured (Non-IP) data. The SCS/AS or AF may send and receive messages to/from a given UE identified by an External Identifier, MSISDN, and/or the like. The UE may have an Unstructured PDU session activated and the message on the Nm or T8 API may be mapped to DL non-IP data PDU or from UL non-IP data PDU delivered to/from the UE. In an example, for the direct model case, the DL and UL data PDUs may be transmitted directly between the UPF and the SCS/AS or AF.

In an example, an SCS/AS or AF may send a MT submit request with small data using T8 API, Nm API, and/or the like to a NEF or a NIMF.

The NIMF/NEF may determine the UE based on established connections and the external identifier or MSISDN included in the MT submit request. The NIMF may perform authorization and quota checks. If there is no established connection corresponding to the external identifier or MSISDN, the NIMF may send a MT submit response with appropriate error cause value. In an example, if there is no established connection corresponding to the external identifier or MSISDN, the NIMF/NEF may perform device triggering towards the UE to establish a connection.

The NIMF may sends a DL data PDU towards the UE using the IP address associated with the connection established by the UE. If the NIMF expects no acknowledgement on the message with the DL data PDU, the NIMF may sends a MT submit response to the SCS/AS informing that an unacknowledged transmission to the UE has been made.

In an example, the UE may send an UL data PDU to the NIMF. The NIMF may determine if the received UL data is an acknowledgement of the DL data. If the UL data PDU is an acknowledgement, the NIMF may send a MT Submit Response to the SCS/AS informing that an acknowledged transmission to the UE has been made.

In an example embodiment, a reliable data service (RDS) may be used by the UE and NEF for reliable (small) data delivery of unstructured PDU. The RDS may provide a mechanism for the NEF to determine if the data was successfully delivered to the UE and for the UE to determine if the data was successfully delivered to the NEF. In an example, when a requested acknowledgement is not received, the reliable data service may retransmit the packet. In an example, the RDS may employ NAS transport between the UE and the AMF for small data delivery. This may apply to both 3GPP and non-3GPP accesses. In an example, the RDS may require support for the AMF determining the NEF for a UE. In an example, the NEF may support subscription checking and actual transmission of MO/MT small data delivery by the NEF to the AF/UE. In an example, the RDS may support MO/MT small data delivery for both roaming and non-roaming scenarios, unstructured PDU, and/or API exposure for reliable data service towards 3rd party application providers.

In an example, during a registration procedure, a UE may provide RDS supported indication over NAS signaling indicating the UE's capability for support of RDS. In an example, the RDS supported indication may indicate whether the UE may support reliable small data delivery over NAS via 3GPP access or via both 3GPP and non-3GPP access. If the core network supports RDS functionality, the AMF may include RDS supported indication to the UE, and whether RDS delivery over NAS via 3GPP access or via both the 3GPP and non-3GPP access is accepted by the network.

In an example, RDS packets may be transmitted over NAS without the need to establish data radio bearers, via NAS transport message, which can carry RDS payload. PDU session establishment may not be needed. The UE and network may support RDS protocol. In an example, when the RDS is enabled, a protocol may be used between the end-points, e.g., between the UE and the NEF. The protocol may employ an RDS header to identify if the packet requires no acknowledgement, requires an acknowledgement, or is an acknowledgment and to allow detection and elimination of duplicate PDUs at the receiving endpoint. In an example, port numbers in the header may be used to identify the application on the originator and to identify the application on the receiver.

An example FIG. 18 depicts data transmission over NAS (e.g., MM-NAS and SM-NAS).

An example FIG. 19 depicts a reliable data service via control plane to an SCS/AS via an NEF. The scenarios depicted in FIG. 19 employ data transmission through AMF and through AMF and SMF.

An example FIG. 20 depicts data transmission via user plane from a wireless device to a data network and to a SCS/AS or an AF. The data transmission may employ an NEF network function with a data transmission support functionality.

An example FIG. 21 depicts an example of a network function registration with an NRF and configuration with an OAM. The network function may be a UPF as depicted in FIG. 21. The network function may be an NEF, NIMF, and/or the like.

A communication system (e.g., 3G, 4G, LTE, 5G, and/or the like) may support (small) data transmission for cellular Internet of things (CIoT) applications. A wireless device may establish a session for transmission of UL and/or DL data that may be via N6 interface to a DN or towards an AF, AS, SCS/AS via an NEF.

The communication system may support data transmission (e.g., for CIoT) and may require to release NAS connection and user plane resources as soon as possible to save UE power, network resources, and/or the like. Release of resources after data transmission may be required for support of small data transmissions, single packet transmission (UL or DL), dual packet transmission (UL with subsequent DL, or DL with subsequent UL), multiple packet transmission (one or a few UL and/or one or a few DL (in any combination or order), and/or the like. When a DL data transmission or data packet transmission is initiated and/or controlled by the network, the existing solutions do not provide an efficient and reliable method for release of resources upon completion of the data packet transmission and may cause inefficient use of network resources.

Example embodiments provide solution on how to provide release assistance indicator (RAI) indicating an end of packet transmission for a packet data unit (PDU) session of a wireless device for downlink data.

Example embodiments provide efficient and reliable method for release of network resources for data packet transmission that is initiated/controlled by the network.

In an example embodiment, a wireless device (a UE) may request release of a connection (e.g., signaling/control plane connection, user plane connection, non-access stratum NAS connection, RRC connection, and/or the like). The UE may send a request that may comprise a release assistance indication/indicator, release assistance information, end of transmission, and/or the like to the network (e.g., to a core network element AMF, SMF, and/or the like or to a base station, RAN, NG-RAN, and/or the like). In an example, the release assistance indicator may be provided by a UE, or by the network e.g., a core network function, a SMF, NEF, AF, SCS/AS, and/or the like. In an example, the release assistance indicator/indication may be employed by the network to inform the network whether or not a downlink/uplink data transmission (e.g. acknowledgement or response) subsequent to the uplink/downlink data transmission is expected. Example FIG. 30, FIG. 31, and FIG. 32 depict examples of information element of a release assistance indication/indicator. In an example, when the release assistance indicator is provided by the UE, the UE may provide the release assistance indicator/indication for uplink data transmission in a non-access stratum (NAS) message e.g., NAS-MM, NAS-SM, and/or the like. The UE may send release assistance indication to the AMF inside a NAS PDU.

In an example, when the AMF receives a release assistance indicator (e.g., from a network element, SMF, NEF, AF, AS, SCS/AS, and/or the like) for downlink data transmission, the AMF may handle the release assistance indicator/indication. If the release assistance indication indicates that no further uplink or downlink data transmissions are expected and unless the AMF is aware of other pending MT traffic, the AMF may request NG-RAN to release the UE context. In an example, the AMF may determine to request release of the UE context based on a status of one or more existing PDU sessions associated with the UE. In an example, the release assistance indication provided by the network (e.g., from AS, SCS/As, AF) may indicate that one or more uplink data transmission subsequent to a downlink data transmission is expected. In an example, the release assistance indication provided by the network (e.g., from AS, SCS/As, AF) may indicate that no downlink transmission subsequent to an uplink/downlink data transmission is expected. In an example, the release assistance indication may indicate that one or more downlink/uplink data transmission subsequent to an uplink/downlink data transmission is expected. The AMF may request the base station (e.g., NG-RAN) to release the UE context once the packet is transmitted to the UE via a UPF and the base station or the AMF has forwarded the downlink NAS transport message with container type “SM data transfer” to the UE unless the AMF is aware of other pending MT traffic.

In an example embodiment, the UE may send release assistance indication/indicator (RAI) via access stratum AS. The RAI may indicate whether further uplink/downlink transmissions or only a single downlink transmission is expected. When NG-RAN receives the RAI from the UE in AS, the NG-RAN may maintain the UE's RRC connection in case RRC connection establishment procedure was performed/executed, and may include an N2 RAI indication (e.g., no further uplink/downlink transmissions or only a single downlink transmission, and/or the like) in a UE message or an uplink NAS transport message. The AMF may evaluate the N2 RAI. If the N2 RAI indicates no further uplink/downlink transmissions and the AMF is not aware of any pending downlink DL data for the UE (e.g. a pending SMS or pending DL data buffered e.g. in SMF/UPF as part of extended buffering), the AMF may send the N2 UE context release command to NG-RAN as per the AN release procedure.

In an example, if the N2 RAI indicates only a single downlink transmission is expected, the AMF may send the N2 UE context release command to NG-RAN as per the AN release procedure once the AMF has forwarded the next downlink NAS transport message with container type “SM data transfer” to the UE and unless the AMF is aware of other pending MT traffic.

The release assistance indication in AS may support UP-based data delivery. In this case the RAN may send the N2 UE context release request including the N2 RAI to the AMF. The AMF may send the N2 UE context release command to NG-RAN unless the AMF is aware of other pending MT traffic. The RAN may release the UE once it has received the N2 UE context release command from the AMF and once an outstanding UP downlink transmission has been received.

In an example, the AN release procedure may comprise sending by the AMF to a base station a context release command. The AMF may send to a base station (RAN, NG-RAN, and/or the like) an N2 UE context release command (e.g., with a cause). The cause may indicate a cause received from (R)AN or a cause due to an AMF internal event. When an NG-RAN is employed, the AMF may send the UE context release command message to the NG-RAN node. The UE context release command message may comprise the AMF UE NGAP ID IE and the RAN UE NGAP ID IE.

Upon reception of the UE context release command message, the NG-RAN node may release signaling and user data transport resources and reply with a UE context release complete message.

If the RAN paging priority IE is included in the UE context release command message, the NG-RAN node may employ the paging priority IE to determine a priority for paging the UE in RRC_INACTIVE state. In an example, a user location information IE may be included in the UE context release complete message. If the information on recommended cells and RAN nodes for paging IE is included in the UE context release complete message, the AMF may store the information and may use it for subsequent paging.

If the (R)AN connection (e.g. RRC connection or NWu connection) with the UE is not already released, the (R)AN may request the UE to release the (R)AN connection. Upon receiving (R)AN connection release confirmation from the UE, the (R)AN may delete the UE's context.

The (R)AN (e.g., 3GPP AN, non-3GPP AN, and/or the like) may confirm the N2 release by returning an N2 UE context release complete (e.g., list of PDU session ID(s) with active N3 user plane, UE radio capability, and/or the like) message to the AMF. The list of PDU session ID(s) may indicate the PDU sessions served by (R)AN of the UE. The AMF may store the UE Radio Capability information received from the NG-RAN node. The N2 signaling connection between the AMF and the (R)AN for the UE may be released. The (R)AN may provide a list of recommended cells/tracking areas TAs/NG-RAN node identifiers for paging to the AMF. In an example, for one or more of the PDU sessions in the N2 UE context release complete, the AMF may invoke a Nsmf_PDUSession_UpdateSMContext Request (e.g., comprising: PDU session ID, PDU session deactivation, cause, operation type, and/or the like). The operation type may be set to UP deactivate to indicate deactivation of user plane resources for the PDU Session. In an example, the SMF may send to a UPF an N4 session modification request (e.g., AN or N3 UPF Tunnel info to be removed, Buffering on/off). The SMF may initiate an N4 session modification procedure indicating the need to remove tunnel info of AN or UPF terminating N3. Buffering on/off may indicate whether the UPF may buffer incoming DL PDU or not.

In an example, the UPF may send to the SMF an N4 session modification response acknowledging the SMF request. In an example, the SMF may send to the AMF an Nsmf_PDUSession_UpdateSMContext Response. Upon completion of the procedure, the AMF may consider the N2 and N3 as released and may enter/transition to CM-IDLE state.

In an example embodiment, one or more PDU sessions may be established for a wireless device (UE) for transmission of data packets. The data packets may be for cellular IoT, small data transmission, and/or the like. The PDU session may be established for transmission of data packets via control plane (as depicted in example FIG. 18 and FIG. 19) or via user plane (as depicted in example FIG. 20). In an example, the data packets may be non-IP data as depicted in example FIG. 17.

In an example, a UPF may receive data packets from a data network (DN) or from an application server (AS), an SCS/AS, an application function (AF), and/or the like. In an example, the UPF may receive the data packets via a network exposure function (NEF). In an example, the NEF, the DN, AS, SCS/AS, or AF may send the data packets to an SMF.

In an example embodiment as depicted in FIG. 22 and FIG. 24, a session or a connection (e.g., a PDU session, non-IP data delivery connection, and/or the like) between a UE and a DN, AS, AF, SCS/AS, and/or the like may be established/configured. Data transmission between the AF, AS, SCS/AS may be via an NEF.

In an example, the AF may send a fourth message to the NEF. In an example, the fourth message may comprise a data packet (e.g., DL data). The fourth message may comprise an RAI (e.g., a release assistance indication/indicator/information, end of data transmission indication, and/or the like). In an example, the data packet may comprise the DL data. In an example, the data packet may comprise the RAI. The data packet transmission may be a packet transmission. In an example, the RAI may indicate that the data packet may be the last data to transmit and one or more uplink data may be expected, or no UL data may be expected. In an example, the RAI may comprise the indication of last packet transmission. If one or more UL data transmission is expected after transmission of the data packet or DL data, the RAI may further comprise a parameter indicating that one or more UL data packets may be transmitted, a number/count of packets, a time value (10 seconds, 20 seconds, and/or the like) indicating a time duration for which UL data may be received, and/or the like. In an example, the parameter may be employed to trigger a resource release e.g., when the expected number of UL packets are received or the duration of the time value is elapsed.

In an example, the NEF may send a first message to the UPF. The first message may comprise the RAI, the data packet, and/or the like. If the first message comprises the data packet or the DL data, the UPF may send/forward the data packet or the DL data to a base station via an N3 interface, N3 tunnel. In an example, the UPF may send/forward the data packet to an intermediate UPF via N9 interface. The UPF may send the data packet to the wireless device via the base station. The UPF may send the data packet to the base station via one or more intermediate UPF(s). In an example, the UPF may receive the first message from the NEF comprising the RAI. The first message may indicate the end of packet transmission, the last packet transmission, and/or the like for a PDU session of the wireless device (UE). The first message may comprise the data packet, the RAI, an identifier of the wireless device, an identifier of an application (application ID) and/or the like. In an example, when a control plane data transmission is employed, the UPF may send/forward the data packet to the SMF.

In an example, the UPF may receive and/or detect the RAI via a packet header, an NIDD service message, and/or the like.

In an example, a proxy function, a CIoT support function, and/or the like may be employed or co-located in the UPF. In an example, the proxy function in the UPF node (e.g., the PSA-UPF) may apply header compression/decompression, ciphering/deciphering, integrity protection, and/or the like.

In an example, PDU session establishment may comprise selecting an NEF for CIoT data transmission, non-IP data delivery NIDD, and/or the like via the UPF and/or the UPF/proxy function. In an example, an interface may be employed for interaction between the UPF and the NEF (e.g., Nx interface, N6m interface, and/or the like). In an example, when the PDU session establishment is performed, based on a subscription data, a DNN, invoke NEF selection indicator, and/or the like, the SMF may select an NEF for NIDD based on a UE subscription profile. The SMF may configure the NEF and UPF anchor (e.g. PDU session anchor, PSA, packet data unit session anchor UPF and/or the like) for data transfer for a UE ID, a PDU session ID, and/or the like. The SMF may update the AMF with an identifier of the NEF (e.g., NEF ID) via the Nsmf_PDUSession_CreateSMContext response in order for the AMF to invoke Namf_EventExposure_Notify (User Identity) service once the UE becomes reachable or is about to become reachable.

In an example, the AF, SCS/AS may activate the NIDD service for the wireless device, UE, and may have data packet (e.g., downlink data, downlink non-IP data, and/or the like) to send to the UE. The AF, or SCS/AS may send the fourth message to the NEF. In an example, the fourth message may be an MT NIDD submit request message comprising an external identifier or GPSI, the data packet, non-IP data, reliable data service configuration, maximum latency, priority, PDU session establishment option, and/or the like) message to the NEF. When the AF may send the last data packet to the UE, the fourth message or the MT NIDD submit request may comprise the release assistance indicator/indication, RAI.

In an example, the NEF may determine the PDU session context based on the DNN associated with the NIDD configuration and the user identity. If an NEF PDU session context corresponding to the external identifier or GPSI included in the MT NIDD submit request is found, the NEF may checks whether the AF or SCS/AS is authorized to send NIDD request, that the AF, or SCS/AS has not exceeded the quota of data submission to the PDU session, and/or the like. In an example, the PDU session establishment option in the MT NIDD submit request message may be employed. Based on the PDU session establishment option, if no NEF PDU session context is found, the NEF, depending/based on the PDU session establishment option, may send a NIDD submit response (cause) with appropriate error cause value. The NEF based on the PDU session establishment option may perform a device triggering procedure towards the UE to establish a PDU session.

In an example, if an NEF PDU session context corresponding to the external identifier or GPSI included in the fourth message (e.g., the MT NIDD submit request message), the NEF may send the first message to the UPF and/or the proxy function. In an example, the first message may be a NIDD submit request message comprising a user identity, PDU session ID, NEF ID, the data packet, non-IP data, NEF wait time, maximum re-transmission time, and/or the like toward the UPF and/or the proxy function. In an example, if the fourth message comprises the RAI, the first message may comprise the RAI.

In an example, the RAI may be transmitted via a packet header or non-IP data packets, IP packets, ethernet, unstructured, and/or the like. In an example, packet header may be employed to transmit the RAI indication. A packet may comprise a payload, a header comprising one or more fields, and/or the like. In an example, one or more fields of the packet header may be employed to indicate RAI, or an end marker. In an example, a flag (one or more bits, a block, and/or the like) of the packet header may be employed to indicate a release request. In an example, a payload of the packet may be employed to transmit and detect the RAI. The packet header may employ/comprise a type, length, value TLV guideline to assist with the detection and/or the detection rules of the packet. In an example, one or more detection rules may be configured in the UPF to detect the RAI.

In an example, the UPF may detect the RAI or may determine that the data packet is the last data packet transmission, or no further downlink or uplink transmission is expected, and may trigger a reporting to the SMF. In an example, when the RAI indicates that UL data may be transmitted/expected after the DL data, the UPF may trigger the reporting procedure based on the indication RAI e.g., detecting the transmission of the UL data, and/or the like. The reporting procedure may be an N4 reporting, PFCP reporting, and/or the like. The PFCP session report procedure may be employed by a UP function (e.g., the UPF) to report information related to the PFCP session to the CP function (e.g., the SMF).

In an example, the UPF may send the RAI to the SMF via a session (e.g., an N4 session. PFCP session, and/or the like) established/configured between the UPF and the SMF for the PDU session of the wireless device. In an example, the UPF may send a second message to the SMF. The second message may indicate a release request. The second message may comprise an identifier of a session between the SMF and the UPF (e.g., an N4 session identifier, PFCP session identifier, and/or the like), the release assistance indicator RAI, and/or the like.

In an example, the second message may be a session report procedure (e.g., N4 reporting, PFCP reporting, and/or the like). The UP function may initiate the PFCP session report procedure to report information related to an PFCP session to the CP function. The UP function may send the PFCP session report request message, identifying the PFCP session for which the report is sent and including the information to be reported. When the UP function receives a PFCP session report response with the cause success, the UP function may consider the information to be successfully delivered to the CP function. When the CP function receives an PFCP session report request message, the CP function (e.g., the SMF) may send the PFCP session report response message with a rejection cause indicating that session context is not found if the F-SEID included in the PFCP session report request message is unknown. The CP function may process the information being reported as appropriate and send an PFCP session report response with the cause indicating success or return an appropriate error cause value.

In an example, when N4 session reporting is employed, the UPF may send an N4 report message (e.g., comprising an N4 session ID, the RAI, list of [reporting trigger, measurement information], and/or the like) to the SMF. In an example, the reporting trigger parameter may comprise the RAI. The reporting trigger parameter may comprise a name of the event which triggered the report and a measurement information parameter that may comprise information that the SMF requested to be informed about. The SMF may identify the N4 session context based on the received N4 session ID and may apply the reported information for the corresponding PDU session. The SMF may respond with an N4 report ACK message.

In an example embodiment, when the SMF receives the RAI from the UPF, the SMF may determine that the PDU session may be deactivated/released. In an example, the SMF may send a session modification request message to the UPF indicating release/deactivation of user plane resources, user plane tunnel, user plane tunnel information associated with the PDU session of the wireless device. The session modification request message may comprise the identifier of the session between the SMF and the UPF (e.g., the N4 session ID, identifier of the PFCP session, and/or the like). In an example, the session modification request message may comprise an N4 session modification request message, a PFCP session modification request, an Sx session modification request, and/or the like.

In an example, the SMF may initiate an N4 session release procedure to release an intermediate UPF of N3 terminating point. If there are one or more intermediate UPFs, the SMF may initiate the N4 release procedure for one or more UPFs (intermediate UPFs) to be released. The SMF may initiate an N4 session modification procedure to the UPF (i.e. N9 terminating point or PDU session anchor) connecting to the released (intermediate) UPF.

In an example, if the intermediate UPF(s) of N3 terminating point is released, the SMF may initiate an N4 Session Modification procedure towards the UPF (PDU Session Anchor or another intermediate UPF) connecting to the released UPF, indicating the need to remove AN tunnel info for N3 tunnel of the PDU session of the wireless device. In an example, the UPF connecting to the released UPF may buffer the DL packets for the PDU session. In an example, N4 session modification procedure may be performed toward the UPF of N3 terminating point.

In an example, if the UPF of N3 terminating point is not released, the SMF may initiates an N4 session modification procedure indicating the need to remove AN tunnel info for N3 tunnel of the PDU session. When the PDU session corresponds to a LADN, the SMF may notify the UPF to discard downlink data for the PDU sessions and/or to not provide further data notification messages.

In an example, the SMF may invoke an Namf_Communication_N1N2MessageTransfer service operation (comprising PDU session ID, N2 SM information (N2 resource release request (PDU Session ID))) to release the NG-RAN resources associated with the PDU Session.

The AMF may send an N2 PDU session resource release command including N2 SM information (N2 resource release request (PDU session ID)) received from the SMF via N2 to the NG-RAN.

The NG-RAN may issue NG-RAN signaling exchange (e.g. RRC connection reconfiguration, and/or the like) with the UE to release the NG-RAN resources related to the PDU session of the wireless device received from the AMF.

The NG-RAN may acknowledge the N2 PDU session resource release command to the AMF including N2 SM resource release ack (user location information).

The AMF may invoke an Nsmf_PDUSession_UpdateSMContext service operation to acknowledge the Namf_Communication_N1N2MessageTransfer service operation.

In an example, when the SMF invokes the Namf_Communication_N1N2MessageTransfer service operation to release the NG-RAN resources associated with the PDU session, the AN release procedure may be performed. The AN release procedure may comprise sending by the AMF to a base station (RAN, NG-RAN, and/or the like) a context release command. The AMF may send to a base station (RAN, NG-RAN, and/or the like) an N2 UE context release command (e.g., with a cause). The cause may indicate a cause received from (R)AN or a cause due to an AMF internal event. When an NG-RAN is employed, the AMF may send the UE context release command message to the NG-RAN node. The UE context release command message may comprise the AMF UE NGAP ID IE and the RAN UE NGAP ID IE.

Upon reception of the UE context release command message, the NG-RAN node may release signaling and user data transport resources and reply with the UE context release complete message.

If the RAN paging priority IE is included in the UE context release command message, the NG-RAN node may employ the paging priority IE to determine a priority for paging the UE in RRC_INACTIVE state. In an example, a user location information IE may be included in the UE context release complete message. If the information on recommended cells and RAN nodes for paging IE is included in the UE context release complete message, the AMF may store the information and may use it for subsequent paging.

If the (R)AN connection (e.g. RRC connection or NWu connection) with the UE is not already released, the (R)AN may request the UE to release the (R)AN connection. Upon receiving (R)AN connection release confirmation from the UE, the (R)AN may delete the UE's context.

The (R)AN may confirm the N2 release by returning an N2 UE context release complete (e.g., list of PDU session ID(s) with active N3 user plane, UE radio capability, and/or the like) message to the AMF. The list of PDU session ID(s) may indicate the PDU sessions served by (R)AN of the UE. The AMF may store the UE Radio Capability information received from the NG-RAN node. The N2 signaling connection between the AMF and the (R)AN for the UE may be released. The (R)AN may provide a list of recommended cells/tracking areas TAs/NG-RAN node identifiers for paging to the AMF. In an example, for one or more of the PDU sessions in the N2 UE context release complete, the AMF may invoke a Nsmf_PDUSession_UpdateSMContext request (e.g., comprising: PDU session ID, PDU session deactivation, cause, operation type, and/or the like). The operation type may be set to UP deactivate to indicate deactivation of user plane resources for the PDU Session. In an example, the SMF may send to a UPF an N4 session modification request (e.g., AN or N3 UPF Tunnel info to be removed, Buffering on/off). The SMF may initiate an N4 session modification procedure indicating the need to remove tunnel info of AN or UPF terminating N3. Buffering on/off may indicate whether the UPF may buffer incoming DL PDU or not.

In an example, the UPF may send to the SMF an N4 session modification response acknowledging the SMF request. In an example, the SMF may send to the AMF an Nsmf_PDUSession_UpdateSMContext Response. Upon completion of the procedure, the AMF may consider the N2 and N3 as released and may enter/transition to CM-IDLE state.

In an example embodiment, a UPF may receive a first message from an NEF. The first message may indicate an end of packet transmission for a PDU session of a wireless device. The first message may comprise an RAI, an identifier of the wireless device, a data packet, and/or the like. The UPF may send/forward the data packet to a base station via an N3 tunnel or to an intermediate UPF via an N9 interface. The UPF may release user plane tunnel, N3 tunnel information, and/or the like associated with the PDU session of the wireless device in response to receiving the first message (e.g., comprising the RAI, the data packet, and/or the like) from the NEF. The UPF may send a second message or a release indication message (e.g., comprising an identifier of a session between the SMF and the UPF, the RAI, and/or the like) via an interface between the UPF and the SMF e.g., N4 interface. The second message or the release indication message may comprise an N4 reporting procedure. The SMF may send an acknowledgment to the UPF indicating the receipt or acknowledgment of the release indication message. The SMF may send/invoke to the AMF and in response to receiving the release indication message, an Namf_Communication_N1N2MessageTransfer service operation (comprising PDU session ID, N2 SM information (N2 resource release request (PDU Session ID))) to release the NG-RAN resources associated with the PDU Session.

In an example embodiment as depicted in FIG. 25, the AF, SCS/AS may send the fourth message to the NEF. The fourth message may comprise the RAI. The NEF may send a first message to the SMF. The first message may comprise the RAI. In an example, the first message may comprise an identifier of the wireless device (e.g., UE ID, an address of UE, SUPI, GPSI, and/or the like), an identifier of the PDU session (e.g., PDU session ID), and/or the like. In an example, when the fourth message comprises the data packet, or DL data, the NEF may send the data packet to the UPF. The UPF may send/forward the data packet, or the DL data to the wireless device via the base station (e.g., via N3 interface, N3 tunnel) or via an intermediate UPF (e.g., via N9 interface).

In an example embodiment, when the SMF receives the RAI from the NEF (e.g., via the first message), the SMF may determine that the PDU session may be deactivated/released. In an example, the SMF may send a session modification request message to the UPF indicating release/deactivation of user plane resources, user plane tunnel information associated with the PDU session of the wireless device. The session modification request message may comprise the identifier of the session between the SMF and the UPF (e.g., the N4 session ID, identifier of the PFCP session, and/or the like).

In an example, the SMF may initiate the N4 session release procedure to release an intermediate UPF of N3 terminating point. If there are one or more intermediate UPFs, the SMF may initiate the N4 release procedure for one or more UPFs (intermediate UPFs) to be released. The SMF may initiate an N4 session modification procedure to the UPF (i.e. N9 terminating point or PDU session anchor) connecting to the released (intermediate) UPF.

In an example, if the intermediate UPF(s) of N3 terminating point is released, the SMF may initiate the N4 session modification procedure towards the UPF (PDU session anchor or one or more intermediate UPF(s)) connecting to the released UPF, indicating the need to remove AN tunnel info for N3 tunnel of the PDU session of the wireless device. In an example, the UPF connecting to the released UPF may buffer the DL packets for the PDU session. In an example, N4 session modification procedure may be performed toward the UPF of N3 terminating point.

In an example, if the UPF of N3 terminating point is not released, the SMF may initiates an N4 session modification procedure indicating the need to remove AN tunnel info for N3 tunnel of the PDU session. When the PDU session corresponds to a LADN, the SMF may notify the UPF to discard downlink data for the PDU sessions and/or to not provide further data notification messages.

In an example, the SMF may send a third message to the AMF. The third message may comprise the RAI, the identifier of the PDU session (e.g., PDU session ID), and/or the like. The third message may be via an interface between the SMF and the AMF (e.g., N11 interface). In an example, the third message may employ an Namf_Communication_N1N2MessageTransfer service operation. In an example, the SMF may invoke the Namf_Communication_N1N2MessageTransfer service operation (comprising PDU session ID, N2 SM information (N2 resource release request (PDU Session ID))) to release the NG-RAN resources associated with the PDU Session.

The AMF may send an N2 PDU session resource release command including N2 SM information (N2 resource release request (PDU session ID)) received from the SMF via N2 to the NG-RAN.

The NG-RAN may issue NG-RAN signaling exchange (e.g. RRC connection reconfiguration, and/or the like) with the UE to release the NG-RAN resources related to the PDU session of the wireless device received from the AMF.

The NG-RAN may acknowledge the N2 PDU session resource release command to the AMF including N2 SM resource release ack (user location information).

The AMF may invoke an Nsmf_PDUSession_UpdateSMContext service operation to acknowledge the Namf_Communication_N1N2MessageTransfer service operation.

In an example, when the SMF invokes the Namf_Communication_N1N2MessageTransfer service operation to release the NG-RAN resources associated with the PDU Session, the AN release procedure may be performed.

In an example embodiment as depicted in FIG. 28, one or more PDU session may be established for a wireless device or associated to the wireless device. In an example, the wireless device may have one or more PDU session(s) associated with one or more AF(s), AS(s), SCS/AS(s), and/or the like. When one or more AF(s) indicate an end of packet transmission to request release of one or more PDU session(s) or release of UE connections (e.g., transmit the RAI), one or more AF(s) may have one or more PDU session(s) that may be active. In an example, the SMF upon receiving the one or more RAI(s) for the one or more PDU session(s) of the wireless device, may determine if the wireless device has one or more PDU sessions that are active and may not send an indication to the AMF to release the UE context or NAS connection of the UE. In an example, the SMF may determine that the one ore RAI(s) or the RAI that is received from the UPF or the NEF is the last RAI and UE signaling, control plane and user plane resources may be released. In an example, the SMF may determine to release the resources based a status of pending data transmission, determining that no UL or DL data transmission is expected, and/or the like.

In an example embodiment, in response to receiving the one or more RAI(s) or the RAI from the UPF or from the NEF, the SMF may send the RAI or the one or more RAI(s) to the AMF. In an example, the AMF may determine to release the UE NAS connection, release UE context, and/or the like. In an example, the determining by the AMF may be based on the UE context information (e.g., one or more PDU sessions may be active), (status of) pending data transmission, and/or the like.

In an example as depicted in FIG. 28, the AMF may receive one or more RAI(s) from one or more SMF(s). The one or more SMF(s) may receive one or more RAI(s) from one or more UPF(s) or one or more NEF(s). The one or more SMF(s) may send the RAI or the one or more RAI(s) to the AMF. In an example, the AMF may determine to release the UE NAS connection, release UE context, and/or the like. In an example, the determining by the AMF may be based on the UE context information (e.g., one or more PDU sessions may be active), (status of) pending data transmission (e.g., pending mobile terminating MT or DL data, UL transmission expected in response to a DL data transmission, DL transmission expected in response to an UL data transmission, and/or the like), and/or the like.

In an example embodiment, the UPF may receive from an NEF, a first message. The first message may comprise a release assistance indicator (RAI). In an example, the first message may comprise a data packet. If the first message comprises the data packet, the UPF may send the data packet to the wireless device via a base station. The UPF may send the data packet to the wireless device via an intermediate UPF and a base station.

In an example, in response to receiving the RAI, the UPF may release user plane resources, user plane tunnel, N3 tunnel information, and/or the like.

The UPF may send the RAI to a SMF via a second message. The second message may indicate a request to release the UE context, release the N4 session (context). The second message may comprise the N4 reporting procedure. The second message may comprise the RAI, an identifier of a session between the SMF and the UPF (e.g., the N4 session, N4 session ID), and/or the like.

The SMF in response to receiving the second message may invoke the Namf_Communication_N1N2MessageTransfer service operation (comprising PDU session ID, N2 SM information (N2 resource release request (PDU Session ID))) to release the NG-RAN resources associated with the PDU Session.

In an example embodiment as depicted in FIG. 27 and FIG. 29, small data fast path (SDFP) transmission may be employed for transmission of data packets, DL data and/or UL data. The SDFP may be realized by providing relevant UPF or PDU session related information to the UE from the network. In an example, the UE may provide the information (e.g., the UPF or PDU session relevant information) to a RAN. The UPF or PDU session relevant information may enable the RAN to determine/derive a path over N3 to the UPF. At UL data arrival the UE may send a packet/data packet comprising the data, the UPF or PDU session relevant information, and/or the like to the RAN. The RAN may forward/send the data packet to the UPF via the N3 interface. In an example, the UPF or PDU session relevant information may be provided to the UE as part of a session management (SM) procedure or UE registration procedures. The SMF may enable one (or more) of the QoS flows for SDFP. The AMF may determine/derive SDFP security information and may provide the information to the SMF. The SMF may retain/store the SDFP security information for the PDU session, and may enable indicated QoS flows and may acknowledge to the AMF that they have been SDFP enabled. In an example, header compression may be supported in the UE and the UPF.

In an example, RAN may store/retain a list of UPFs that support SDFP, with an index and an IP address for one or more UPF(s) in the list. The list of UPFs supporting SDFP may be preconfigured in the RAN and one or more RAN node(s) in the same UPF service area may have the same information. In an example, when a PDU session is created for SDFP, or activated by SMF, RAN may receive from the AMF/SMF a UPF tunnel information and a SDFP indication. Based on the IP address in the UPF tunnel information and the RAN list of UPFs with SDFP support, RAN may determine the UPF index. RAN may send the UPF index and the UPF N3 UL TEID to the UE.

In an example, when an UL data transmission is required, the UE may send UL data packets by employing SDFP.

The UE may establish an RRC connection for SDFP transfer. The UE may provide parameters for selection of UPF for the PDU session for the UE to the RAN e.g., the UPF index and the UPF UL TEID. In an example, the parameters may be transmitted as part of UL data PDU.

In an example, the AMF may trigger paging towards RAN (e.g. due to N1 CP signaling) during an ongoing SDFP transfer initiated by UL data, RAN may set up N2 UE association using the 5G S-TMSI received from the UE and may provide the AMF with NGAP RAN UE ID. The AMF may reply with NGAP AMF UE ID.

The UE may encrypt, and integrity protect a data packet or an UL data PDU and may send it to the RAN.

The RAN may send/forward the UL data PDU on the N3 tunnel to a selected UPF. RAN may select the UPF and the N3 tunnel based on the SDFP information provided by the UE (i.e. UPF index and the UPF UL TEID) and the RAN preconfigured list of UPFs supporting SDFP. The RAN may provide the UPF with RAN N3 DL Tunnel Info for the SDFP session.

The UPF may check integrity protection and decrypt the UL data PDU. If passed the check, the UPF send/forward the UL data on the N6/N9 interface to a DN or to the NEF towards an AF, AS, SCS/AS, and/or the like. The UPF may enable (subsequent) DL data transmissions to the RAN node when it receives the UP data PDU from N6/N9 interface or the DN, AF, SCS/AS, and/or the like. In an example, a DL data packet may arrive on N6/N9, e.g. an acknowledgement.

The UPF may encrypt and integrity protect the DL data PDU and may send/forward it to the RAN node. The RAN node may forward the DL data PDU to the UE.

In an example, based on a UP activity timeout timer in RAN and UPF the SDFP information context in RAN may be released and DL data transmission in the UPF may be disabled by setting the SDFP in a non-active state. In an example, the RAN node may release the RRC connection.

In an example embodiment, when the UPF receives a first message comprising a data packet and the RAI, release assistance indication/indicator, release assistance information, and/or the like, the UPF may disable DL data transmission in the UPF. The UPF may set/transition the state of SDFP to a non-active state. In an example, the UPF may send the data packet with the RAI to the UE via the RAN node. In response to receiving the RAI by the UE, the UE may send the RAI to the AMF and the AMF may initiate a release of NAS signaling and/or the RRC connection. In an example, the AMF may indicate to the RAN node to release the SDFP information context in the RAN node. In an example, the UPF may send the data packet with the RAI to the RAN node and in response to receiving the RAI, the RAN node may detect the RAI indication and may release the SDFP information context in the RAN node.

In an example, SDFP may be initiated by DL data transmission. In an example, the DL data may be received by the UPF from a DN via N6 interface, or from the NEF. In an example, the DL data received by the UPF (e.g., from N6 or NEF) may be for a PDU session that is SDFP enabled. In an example the SDFP may require activation when the RAN N3 DL TEID is unknown or expired.

In an example, the PDU Session may be in CM_IDLE. The UPF may send a data notification (e.g., downlink data notification) to the SMF. The SMF may notifies the AMF via N11 interface and may employ an Namf_MT_EnableUEReachability service that may comprise a fast Path indicator for DL SDFP transfer. The AMF may send a paging message to the RAN with a fast path FP indicator. The RAN may page the UE with the FP indicator included.

The UE may respond to the paging with an RRC establishment including a NAS service request. The fast path indicator in the received paging may trigger the UE to include the UPF index and UPF UL TEID and a PDU session ID. As part of the RRC establishment, the RAN and the UE may establish a data radio bearer (DRB) with default parameters for SDFP transmissions.

In an example, RAN may determine/detect/understand based on the included UPF index and UPF UL TEID that a SDFP may be established. The RAN node may allocate a RAN N3 TEID, and may map it to the DRB and may establish a N3 tunnel based on the SDFP information provided by the UE (e.g., UPF index and the UPF UL TEID) and the RAN preconfigured list of UPFs supporting SDFP. The RAN node may send an initial UE message (e.g., NAS: service request, RAN N3 TEID, PDU session ID, and/or the like) to AMF.

The AMF may receive NAS service request as a response to the paging request. AMF send a Nsmf_PDUSession_UpdateSMContext request message with the NAS service request, RAN N3 TEID, PDU session ID included to the SMF which may handles the PDU session.

The SMF may determine/detect/understand based on the included RAN N3 TEID that the PDU session may be moved/transitioned to active SDFP state. The SMF may sends an N4 session modification request (comprising RAN N3 TEID, PDU Session, Fast Path indicator, and/or the like) to the UPF. The UPF may store the RAN N3 TEID for the PDU session and may open/activate the PDU session for SDFP transmissions. The UPF may acknowledge to the SMF by sending a N4 session modification response message. The SMF may keep the UE in CM-IDLE and/or may keep a record of the SDFP transmission, e.g. in charging information, statistics, and/or the like. The SMF may acknowledge to the AMF by sending a Nsmf_PDUSession_UpdateSMContext response to the AMF. The UPF may send/forward any buffered DL data to the RAN. The RAN node may send/forward DL data to the UE.

In an example, when the UP activity timeout timer expires in UPF and RAN, the RAN may release the RRC connection, and the UPF may disable the SDFP and transition to non-active state.

In an example, based on a UP activity timeout timer in RAN and UPF the SDFP information context in RAN may be released and DL data transmission in the UPF may be disabled by setting the SDFP in a non-active state. In an example, the RAN node may release the RRC connection.

In an example embodiment, when the UPF receives a first message comprising a data packet and the RAI, release assistance indication/indicator, release assistance information, and/or the like, the UPF may disable DL data transmission in the UPF. The UPF may set/transition the state of SDFP to a non-active state. In an example, the UPF may send the data packet with the RAI to the UE via the RAN node. In response to receiving the RAI by the UE, the UE may send the RAI to the AMF via a NAS message and the AMF may initiate the release of NAS signaling and/or the RRC connection. In an example, the AMF may indicate to the RAN node to release the SDFP information context in the RAN node. In an example, the UPF may send the data packet with the RAI to the RAN node and in response to receiving the RAI, the RAN node may send the data packet and the RAI to the UE. The RAN node may detect the RAI indication and may release the SDFP information context in the RAN node. The RAN node based on the RAI may send a release request message to the AMF via N2 and the AMF may release the UE context and may initiate the release of NAS connection, RRC connection, and/or the like.

In an example embodiment, a user plane function (UPF) may receive from a network exposure function (NEF), a first message. The first message may comprise a release assistance indicator indicating end of packet transmission for a packet data unit session of a wireless device. The UPF may send to a session management function (SMF), a second message indicating a release request. The second message may comprise an identifier of a session between the SMF and the UPF, the release assistance indicator, and/or the like. The UPF may receive from the SMF, a session modification request message indicating release of user plane tunnel and/or tunnel information. The session modification request message may comprise the identifier of the session between the SMF and the UPF. In an example, the UPF may release based on the session modification request message, the user plane tunnel of the packet data unit session of the wireless device.

In an example, the SMF may send to an access and mobility management function (AMF), a third message. The third message may comprise the release assistance indicator, an identifier of the packet data unit session, and/or the like.

In an example, the AMF may determine to release a non-access stratum connection of the wireless device. In an example, the AMF may determine to release the non-access stratum connection of the wireless device based on pending data packets for at least one packet data unit session of the wireless device. In an example, the release request may indicate deactivation of the packet data unit session of the wireless device. In an example, the identifier of the session may comprise an N4 session identifier of an N4 session.

In an example, the NEF may receive from an application function, a fourth message comprising the release assistance indicator. The fourth message may comprise a data packet, and/or the like. The fourth message may comprise an identifier of the wireless device, and/or the like.

In an example, the first message may comprise a data packet, and/or the like. The UPF may determine, based on the indication, that the data packet may be a last data packet for the packet data unit session to transmit.

In an example, the UPF may send to a base station, the data packet.

In an example, the first message may comprise an identifier of the wireless device, and/or the like.

In an example, the UPF may send to the base station, the data packet via an intermediate UPF. The UPF may be a packet data unit session anchor UPF (PSA-UPF).

In an example, the AMF may send to a base station a context release command. The context release command message may comprise the AMF UE NGAP ID IE, the RAN UE NGAP ID IE, and/or the like. The base station may release signaling resources and user data resources associated with the wireless device. The base station may send to the AMF, a context release complete message indicating a result of the context release command.

In an example, the SMF may determine to send the release assistance indicator to an AMF. In an example, the determining may be based on a status of at least one packet data unit session associated with the wireless device.

In an example embodiment, a session management function (SMF) may receive from a user plane function (UPF), a first message. The first message may comprise a release assistance indicator indicating end of packet transmission for a packet data unit session of a wireless device. The SMF may send, to the UPF a session modification request message. The session modification request message may indicate release of user plane tunnel. The session modification request message may comprise the identifier of a session between the SMF and the UPF, and/or the like. The SMF may send to an access and mobility management function (AMF), a third message. The third message may indicate release of a non-access stratum connection associated with the wireless device. The third message may comprise the release assistance indicator, an identifier of the packet data unit session, and/or the like.

In an example embodiment, a session management function (SMF) may receive from a network exposure function (NEF), a first message. The first message may comprise a release assistance indicator that may indicate end of packet transmission for a packet data unit session of a wireless device.

In an example, the SMF may send to a user plane function (UPF), a session modification request message. The session modification request message may indicate release of user plane tunnel, (and/or tunnel information). The session modification request message may comprise the identifier of a session between the SMF and the UPF.

In an example, the SMF may send to an access and mobility management function (AMF), a third message indicating release of a non-access stratum connection associated with the wireless device. The third message may comprise the release assistance indicator, an identifier of the packet data unit session, and/or the like.

In an example, the NEF may send to the UPF a data packet. In an example, the first message may comprise a data packet. In an example, the SMF may receive a data packet from the NEF. The SMF may send/forward the data packet to the UPF via the session between the SMF and the UPF.

In an example, the UPF may send to a base station the data packet.

In an example, the AMF may send to a base station a context release command message. The context release command message may comprise an AMF UE NGAP ID IE, a RAN UE NGAP ID IE, and/or the like.

In an example, the base station may release signaling resources and user data resources associated with the wireless device. the base station may send to the AMF, a context release complete message indicating a result of the context release command.

In an example, the SMF may determine to send the release assistance indicator to an AMF. The determining may be based on a status of at least one packet data unit session associated with the wireless device. The AMF may determine to release a non-access stratum connection of the wireless device. The may AMF determine to release the non-access stratum connection of the wireless device based on pending data packets for at least one packet data unit session of the wireless device.

In an example embodiment, a user plane function (UPF) may receive from a network exposure function (NEF), a first message comprising a release assistance indicator. The indicator may indicate end of packet transmission for a packet data unit session of a wireless device.

In an example, the UPF may send to a session management function (SMF), a second message. The second message may indicate a release request. The second message may comprise an identifier of a session between the SMF and the UPF, the release assistance indicator, and/or the like. The UPF may release based on the indication, a user plane tunnel of the packet data unit session of the wireless device.

In an example, the SMF may send to an access and mobility management function (AMF), a third message. The third message may comprise the release assistance indicator, an identifier of the packet data unit session, and/or the like.

In an example, the AMF may determine to release a non-access stratum connection of the wireless device. The AMF may determine to release the non-access stratum connection of the wireless device based on pending data packets for at least one packet data unit session of the wireless device.

In an example, the release request may indicate deactivation of the packet data unit session of the wireless device.

In an example, identifier of the session between the SMF and the UPF may be an N4 session identifier of an N4 session.

In an example, the NEF may receive from an application function, a fourth message. The fourth message may comprise the data packet, the release assistance indicator, and/or the like.

In an example, the first message may comprise a data packet.

In an example, the UPF may determine based on the indication, that the data packet is a last data packet for the packet data unit session to transmit. The UPF may send to a base station, the data packet.

According to various embodiments, a device such as, a SMF, a UPF, an NEF, a wireless device, a base station, and/or the like, may comprise one or more processors and memory. The memory may store instructions that, when executed by the one or more processors, cause the device to perform a series of actions. Embodiments of example actions are illustrated in the accompanying figures and specification. Features from various embodiments may be combined to create yet further embodiments.

FIG. 37 is a flow diagram as per an aspect of an example embodiment of the present disclosure. At 3710, a session management function (SMF) receives a message from a network exposure function (NEF). The message comprises downlink data and a release assistance indicator (RAI). The RAI indicates that transmission of uplink data by a wireless device is expected subsequent to transmission of the downlink data. The RAI indicates a release of a connection associated with the wireless device after the transmission of uplink data. At 3720, the SMF receives an indication that the uplink data is transmitted. At 3730, the SMF upon receiving the indication, sends a release message to an access and mobility management function (AMF). The release message indicates release of a non-access stratum message associated with the wireless device. The release message comprises the release assistance indicator.

According to an example embodiment, the AMF may send to a base station a context release command message. The context release command message may comprise an AMF UE next generation application protocol identifier information element (NGAP ID IE), a radio access network (RAN) UE NGAP ID IE, and/or the like. According to an example embodiment, the base station may release signaling resources of the wireless device in response to the context release command message. According to an example embodiment, the base station may send to the AMF, a context release complete message indicating a result of the context release command message. According to an example embodiment, the sending of the release message may be based on a status of a packet data unit session associated with the wireless device. According to an example embodiment, the status of the Packet Data Unit (PDU) session may indicate that the PDU session is the last PDU session of the wireless device. According to an example embodiment, the AMF may determine to release the non-access stratum connection of the wireless device. According to an example embodiment, the AMF may determine to release the non-access stratum connection of the wireless device based on pending data packets for a packet data unit session of the wireless device. According to an example embodiment, the AMF may determine to release the non-access stratum connection of the wireless device based on a status of a PDU session of the wireless device indicating whether the PDU session is the last active PDU session. According to an example embodiment, the SMF may send to a user plane function, a session modification request message in response to receiving the RAI. According to an example embodiment, the session modification request message may comprise an identifier of a session between the SMF and the User Plane Function. According to an example embodiment, the session modification request message may comprise an identifier of an indication to release an access network tunnel for the wireless device. According to an example embodiment, the SMF may send to the wireless device, the downlink data. According to an example embodiment, the SMF may send the downlink data to the wireless device via the AMF. According to an example embodiment, the SMF may send the downlink data to the wireless device via a user plane function. According to an example embodiment, the transmission of the uplink data and the transmission of the downlink data may be part of the same PDU session. According to an example embodiment, the indication that the uplink data is transmitted comprises the uplink data. According to an example embodiment, the RAI may comprise a packet count parameter indicating a number of expected uplink data packets. According to an example embodiment, the release message may comprises an identifier of a packet data unit session of the wireless device. According to an example embodiment, the RAI may comprise an information element. The information element may comprise an indication that no further transmission of the uplink data subsequent to a transmission of the downlink data is expected. The information element may comprise an indication that a transmission of the uplink data subsequent to a transmission of the downlink data is expected. According to an example embodiment, the RAI may comprise a packet count associated with the transmission of the uplink data. The RAI may comprise a time duration parameter indicating a time duration for which UL data is expected.

In this disclosure, “a” and “an” and similar phrases are to be interpreted as “at least one” or “one or more.” Similarly, any term that ends with the suffix “(s)” is to be interpreted as “at least one” or “one or more.” In this disclosure, the term “may” is to be interpreted as “may, for example.” In other words, the term “may” is indicative that the phrase following the term “may” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. If A and B are sets and every element of A is also an element of B, A is called a subset of B. In this specification, only non-empty sets and subsets are considered. For example, possible subsets of B={cell1, cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on” is indicative that the phrase following the term “based on” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The phrase “in response to” is indicative that the phrase following the phrase “in response to” is an example of one of a multitude of suitable possibilities that may, or may not, be employed to one or more of the various embodiments. The terms “including” and “comprising” should be interpreted as meaning “including, but not limited to.” In this disclosure, the abbreviation “e.g.” means “for example” and is followed by one or more examples that illustrate a term receding the abbreviation.

In this disclosure and the claims, differentiating terms like “first,” “second,” “third,” identify separate elements without implying an ordering of the elements or functionality of the elements. Differentiating terms may be replaced with other differentiating terms when describing an embodiment.

In this disclosure, various embodiments are disclosed. Limitations, features, and/or elements from the disclosed example embodiments may be combined to create further embodiments within the scope of the disclosure.

In this disclosure, parameters (Information elements: IEs) may comprise one or more objects, and each of those objects may comprise one or more other objects. For example, if parameter (IE) N comprises parameter (IE) M, and parameter (IE) M comprises parameter (IE) K, and parameter (IE) K comprises parameter (information element) J, then, for example, N comprises K, and N comprises J. In an example embodiment, when one or more messages comprise a plurality of parameters, it implies that a parameter in the plurality of parameters is in at least one of the one or more messages, but does not have to be in each of the one or more messages.

Furthermore, many features presented above are described as being optional through the use of “may” or the use of parentheses. For the sake of brevity and legibility, the present disclosure does not explicitly recite each and every permutation that may be obtained by choosing from the set of optional features. However, the present disclosure is to be interpreted as explicitly disclosing all such permutations. For example, a system described as having three optional features may be embodied in seven different ways, namely with just one of the three possible features, with any two of the three possible features or with all three of the three possible features.

Many of the elements described in the disclosed embodiments may be implemented as modules. A module is defined here as an isolatable element that performs a defined function and has a defined interface to other elements. The modules described in this disclosure may be implemented in hardware, software in combination with hardware, firmware, wetware (i.e. hardware with a biological element) or a combination thereof, all of which are behaviorally equivalent. For example, modules may be implemented as a software routine written in a computer language configured to be executed by a hardware machine (such as C, C++, Fortran, Java, Basic, Matlab or the like) or a modeling/simulation program such as Simulink, Stateflow, GNU Octave, or LabVIEWMathScript. Additionally, it may be possible to implement modules using physical hardware that incorporates discrete or programmable analog, digital and/or quantum hardware. Examples of programmable hardware comprise: computers, microcontrollers, microprocessors, application-specific integrated circuits (ASICs); field programmable gate arrays (FPGAs); and complex programmable logic devices (CPLDs). Computers, microcontrollers and microprocessors are programmed using languages such as assembly, C, C++ or the like. FPGAs, ASICs and CPLDs are often programmed using hardware description languages (HDL) such as VHSIC hardware description language (VHDL) or Verilog that configure connections between internal hardware modules with lesser functionality on a programmable device. Finally, it needs to be emphasized that the above mentioned technologies are often used in combination to achieve the result of a functional module.

The disclosure of this patent document incorporates material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, for the limited purposes required by law, but otherwise reserves all copyright rights whatsoever.

While various embodiments have been described above, it should be understood that they have been presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art(s) that various changes in form and detail can be made therein without departing from the scope. In fact, after reading the above description, it will be apparent to one skilled in the relevant art(s) how to implement alternative embodiments. Thus, the present embodiments should not be limited by any of the above described exemplary embodiments. In particular, it should be noted that, for example purposes, the above explanation has focused on mission critical services such as mission critical push-to-talk services employing media types such as audio services, video services and media services. However, one skilled in the art will recognize that embodiments of the invention may also be implemented in a system comprising other types of services such as, for example, data services, augmented reality services, data fusion services, combinations thereof, and/or the like.

In addition, it should be understood that any figures which highlight the functionality and advantages, are presented for example purposes only. The disclosed architecture is sufficiently flexible and configurable, such that it may be utilized in ways other than that shown. For example, the actions listed in any flowchart may be re-ordered or only optionally used in some embodiments.

Further, the purpose of the Abstract of the Disclosure is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientists, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The Abstract of the Disclosure is not intended to be limiting as to the scope in any way.

Finally, it is the applicant's intent that only claims that include the express language “means for” or “step for” be interpreted under 35 U.S.C. 112. Claims that do not expressly include the phrase “means for” or “step for” are not to be interpreted under 35 U.S.C. 112. 

What is claimed is:
 1. A method comprising: receiving, by a session management function (SMF) from a network exposure function (NEF), a message comprising: downlink data from an application server and for transmission to a wireless device; and a release assistance indicator (RAI), the RAI indicating: transmission of uplink data by the wireless device is expected subsequent to transmission of the downlink data; and a release of a connection associated with the wireless device after the transmission of the uplink data; receiving, by the SMF, an indication that the uplink data is transmitted; and sending, by the SMF to an access and mobility management function (AMF) based on receiving of the indication, a release message indicating release of a non-access stratum connection associated with the wireless device, the release message comprising the RAI.
 2. The method of claim 1, wherein the AMF sends to a base station a context release command message comprising: an AMF UE next generation application protocol identifier information element (NGAP ID IE); and a radio access network (RAN) UE NGAP ID IE.
 3. The method claim 2, wherein the base station releases signaling resources of the wireless device in response to the context release command message.
 4. The method of claim 3, wherein the base station sends to the AMF, a context release complete message indicating a result of the context release command message.
 5. The method of claim 1, wherein the sending of the release message is based on a status of a packet data unit session associated with the wireless device.
 6. The method of claim 5, wherein the status of the Packet Data Unit (PDU) session indicates that the PDU session is the last PDU session of the wireless device.
 7. The method of claim 1, wherein the AMF determines to release the non-access stratum connection of the wireless device.
 8. The method of claim 7, wherein the AMF determines to release the non-access stratum connection of the wireless device based on pending data packets for a packet data unit session of the wireless device.
 9. The method of claim 7, wherein the AMF determines to release the non-access stratum connection of the wireless device based on a status of a PDU session of the wireless device indicating whether the PDU session is the last active PDU session.
 10. The method of claim 1, further comprising sending by the SMF to a user plane function, a session modification request message in response to receiving the RAI.
 11. The method of claim 10, wherein the session modification request message comprises: an identifier of a session between the SMF and the User Plane Function; and an indication to release an access network tunnel for the wireless device.
 12. The method of claim 1, further comprising sending, by the SMF to the wireless device, the downlink data.
 13. The method of claim 12, wherein the SMF sends the downlink data to the wireless device via the AMF.
 14. The method of claim 12, wherein the SMF sends the downlink data to the wireless device via a user plane function.
 15. The method of claim 1, wherein the transmission of the uplink data and the transmission of the downlink data are part of the same PDU session.
 16. The method of claim 1, wherein the indication that the uplink data is transmitted comprises the uplink data.
 17. The method of claim 1, wherein the RAI further comprises a packet count parameter indicating a number of expected uplink data packets.
 18. The method of claim 1, wherein the release message further comprises an identifier of a packet data unit session of the wireless device.
 19. The method of claim 1, wherein the RAI comprises an information element comprising an indication that: no further transmission of the uplink data subsequent to a transmission of the downlink data is expected; or a transmission of the uplink data subsequent to a transmission of the downlink data is expected.
 20. The method of claim 19, wherein the RAI further comprises: a packet count associated with the transmission of the uplink data; and a time duration parameter indicating a time duration for which UL data is expected. 